Spoth, R., Redmond, C., & Lepper, H. (1999). Alcohol initiation outcomes of universal family-focused preventive interventions: One- and two-year follow-ups of a controlled study. Journal of Studies on Alcohol, s13, 103–111. https://doi.org/10.15288/jsas.1999.s13.103

Type of Study: Randomized controlled trial
Number of Participants: 446 families

Population:

• Age — Children: 10–13 years; Parents: Mean=37.3–40.1 years
• Race/Ethnicity — Children: Not specified; Parents: 99% Caucasian
• Gender — Children: 55% Female; Parents: Not specified
• Status — Participants were 6th graders and their families.

Location/Institution: Twenty-two rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to evaluate the long-term effects of the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] on alcohol initiation. Participants were randomized into an ISFP or control group. Measures utilized include the Alcohol Initiation Index (AII). Results indicate that all scores were significantly lower among ISFP adolescents than among control group adolescents at 1- and 2-year follow-up assessments. Relative-reduction rate differences between intervention and control groups on specific alcohol initiation behaviors (e.g., onset of drinking without parental permission, onset of drunkenness) ranged from approximately 30% to 60%. Dosage-related initiation differences were evident only at the 1-year follow-up. Limitations include reliance on self-report measures, small sample size in the high-risk group, and lack of generalizability of results to nonrural and more ethnically diverse populations.

Length of controlled postintervention follow-up: 1 and 2 years.

Spoth, R., Reyes, M. L., Redmond, C., & Shin, C. (1999). Assessing a public health approach to delay onset and progression of adolescent substance use: Latent transition and loglinear analyses of longitudinal family preventive intervention outcomes. Journal of Consulting and Clinical Psychology, 67(5), 619–630. https://doi.org/10.1037/0022-006X.67.5.619

Type of Study: Randomized controlled trial
Number of Participants: 329 families

Population:

• Age — Children: 10–13 years; Parents: Mean=37.0–39.5 years
• Race/Ethnicity — Children: Not specified; Parents: 99% Caucasian
• Gender — Children: 54% Female; Parents: Not specified
• Status — Participants were 6th graders and their families.

Location/Institution: Thirty-three rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999). The purpose of the study was to evaluate the effects of the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] and the Preparing for the Drug-Free Years Program (PDFY) on young adolescent transitions from nonuse of substances to initiation and progression of substance use. Participants were randomized into PDFY, ISFP, or control group. Measures utilized include the Iowa Department of Education Survey. Results indicate that there were positive intervention results for both ISFP and PDFY. Although substance use rates increased among all groups over the course of the study, the likelihood of substance use initiation at the 2-year follow-up was significantly lower among ISFP adolescents. Both ISFP and PDFY showed significantly lower probabilities of transitions from the no-use status to a use status for the 1-year follow-up to 2-year follow-up period. Limitations include reliance on self-report measures, small sample size in the high-risk group, and lack of generalizability of results to nonrural and more ethnically diverse populations.

Length of controlled postintervention follow-up: 1 and 2 years.

Spoth, R. L., Redmond, C., & Shin, C. (2001). Randomized trial of brief family interventions for general populations: Adolescent substance use outcomes 4 years following baseline. Journal of Consulting and Clinical Psychology, 69(4), 627–642. https://doi.org/10.1037/0022-006X.69.4.627

Type of Study: Randomized controlled trial
Number of Participants: 446 families

Population:

• Age — Children: 10–13 years; Parents: Mean=37.3–40.1 years
• Race/Ethnicity — Children: Not specified; Parents: 99% Caucasian
• Gender — Children: 55% Female; Parents: Not specified
• Status — Participants were 6th graders and their families.

Location/Institution: Thirty-three rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999). The purpose of the study was to evaluate the effects of the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] on adolescents’ exposure to opportunities for substance use and on illicit substance use in the long term. Public schools (N=22) were randomly assigned to ISFP, the Preparing for the Drug Free Years program (PDFY), or a control condition. Measures utilized include self-report of lifetime and current substance use and frequency of use. Results indicate that both PDFY and ISFP showed differences in delayed initiation, current use, and composite use of substances at a point when students are in high-risk years for substance-related problem behaviors. More specifically, mean substance use rates among ISFP adolescents were in the range of one quarter to one third of a standard deviation lower than those of the normal population control group. Limitations include reliance on self-report measures, data from PDFY was omitted, and lack of generalizability of results to nonrural and more ethnically diverse populations.

Length of controlled postintervention follow-up: Approximately 3 years.

Spoth, R. L., Redmond, C., Trudeau, L., & Shin, C. (2002). Longitudinal substance initiation outcomes for a universal preventive intervention combining family and school programs. Psychology of Addictive Behaviors, 16(2), 129–134. https://doi.org/10.1037/0893-164X.16.2.129

Type of Study: Randomized controlled trial
Number of Participants: 2127 families

Population:

• Age — 7th grade at baseline
• Race/Ethnicity — 96% White
• Gender — 53% Male
• Status — Participants were 7th grade students.

Location/Institution: Thirty-three rural schools in 22 contiguous counties in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to evaluate the substance initiation effects of an intervention combining family and school-based competency-training intervention components. Schools were assigned to the school-based Life Skills Training (LST) plus Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14) (LST + SFP 10–14), LST-only, or a control condition. Measures utilized include the Substance Initiation Index (SII), and self-reported lifetime use of alcohol, cigarettes, and marijuana. Results indicate that there were significant effects for both the LST + SFP 10–14 and LST-only interventions on the SII and on marijuana initiation. Relative reduction rates for alcohol initiation were 30.0% for the LST + SFP 10–14 intervention and 4.1% for LST only. Limitations include inability to determine the separate effect of each intervention, generalize to nonrural populations, rural populations in other regions of the country, or populations with different ethnic compositions; missing data; and reliance on self-reported measures.

Length of controlled postintervention follow-up: 1 year.

Spoth, R., Redmond, C., Shin, C., & Azevedo, K. (2004). Brief family intervention effects on adolescent substance initiation: School-level growth curve analyses 6 years following baseline. Journal of Consulting and Clinical Psychology, 72(3), 535–542. https://doi.org/10.1037/0022-006X.72.3.535

Type of Study: Randomized controlled trial
Number of Participants: 667 parent-youth dyads

Population:

• Age — Mean=11.8 years (baseline); Mean=18.2 years (follow-up
• Race/Ethnicity — Not specified
• Gender — Not specified
• Status — Participants were parents and their 6th grade children.

Location/Institution: Thirty-three rural schools in 22 contiguous counties in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used samples from Spoth et al. (1999) and Spoth et al. (2001). The purpose of the study was to evaluate the effects of Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14) and Preparing for the Drug Free Years Program (PDFY) on the trajectories of substance initiation over a period of 6 years following a baseline assessment. Public schools were randomly assigned to the ISFP, the PDFY, or a minimal-contact control condition. Measures utilized include the Alcohol Composite Use Index (ACUI). Results indicate that the ISFP and control groups showed significant condition differences in the rates of growth for three of the seven substance use outcomes examined. For lifetime use of alcohol, lifetime cigarette use, and lifetime use of marijuana, significant negative values indicate slower overall growth in substance use among ISFP-condition adolescents relative to controls. The results also showed that both family-focused interventions slowed the growth in initiation of some substances over a 6-year period following the baseline assessment, during which the mean age of participants increased from 11.8 years to 18.2 years. Limitations include reliance on self-report data of substance use, the degree to which the study findings generalize to more diverse or urban populations is unclear, and high attrition rate.

Length of controlled postintervention follow-up: 6 years.

Spoth, R., Randall, G. K., Shin, C., & Redmond, C. (2005). Randomized study of combined universal family and school preventive interventions: Patterns of long-term effects on initiation, regular use, and weekly drunkenness. Psychology of Addictive Behaviors, 19(4), 372–381. https://doi.org/10.1037/0893-164X.19.4.372

Type of Study: Randomized controlled trial
Number of Participants: 1,650 parent-youth dyads

Population:

• Age — 7th grade at baseline
• Race/Ethnicity — Not specified
• Gender — Not specified
• Status — Participants were parents and their 7th grade children.

Location/Institution: Thirty-six rural schools in 22 contiguous counties in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study included samples from Spoth et al. (1999) and Spoth et al. (2001). The purpose of the study was to report findings on Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14), and Life Skills Training (LST) from an in-school assessment 2.5 years past baseline, as a follow-up to an earlier study of substance initiation. Rural schools were randomly assigned to a) LST + SFP 10–14, b) LST, or c) a control condition. Measures utilized include the Regular Alcohol Use (RAU). Results indicate that the earlier significant outcome on a substance initiation index was replicated, and positive point-in-time results for weekly drunkenness were observed, but there were no statistically significant outcomes for regular alcohol use. Limitations include lack of generalizability due to population sample, and reliance on self-reported measures.

Length of controlled postintervention follow-up: Not specified

Spoth, R., Clair, S., Shin, C., & Redmond, C. (2006). Long-term effects of universal preventive interventions on methamphetamine use among adolescents. Archives of Pediatric and Adolescent Medicine, 160(9), 876–882. https://doi.org/10.1001/archpedi.160.9.876

Type of Study: Randomized controlled trial
Number of Participants: Study 1: 667; Study 2: 2127

Population:

• Age — Study 1: 6th grade at baseline; Study 2: 7th grade at baseline
• Race/Ethnicity — Study 1: 98% White; Study 2: 99% White
• Gender — Not specified
• Status — Study 1: Participants were 6th grade students at study enrollment; Study 2: Participants were 7th grade students at study enrollment.

Location/Institution: Rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to examine the long-term effects of universal preventive interventions on methamphetamine use by adolescents in the general population during their late high school years. For Study 1: Schools were randomly assigned to either a minimal contact control group or 1 of 2 experimental groups: Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)], or the 5-session Preparing for the Drug Free Years (PDFY). For Study 2: Three schools in each block were randomly assigned to each of the 3 experimental groups: the SFP 10–14 combined with the Life Skills Training (LST) program (SFP 10–14+ LST), the LST only, or a minimal-contact control group. Measures utilized include self-reports of lifetime and past-year prescription drug misuse. Results indicate that, in Study 1, the ISFP past-year rate was significantly lower than the control group. In Study 2, SFP 10–14 + LST showed significant effects on lifetime and past-year use at the 4½ year follow-up; both SFP 10–14 + LST and LST alone had significant lifetime use effects at the 5½ year follow-up. Limitations include lack of generalizability to nonrural populations, rural populations in other regions of the country, or populations with different ethnic compositions; the lack of an SFP 10–14 only group in Study 2; and the limited numbers of methamphetamine users in the sample, which affected the analyses that were possible.

Length of controlled postintervention follow-up: Approximately 5 years.

Trudeau, L., Spoth, R., Randall, G. K., & Azevedo, K. (2007). Longitudinal effects of a universal family-focused intervention on growth patterns of adolescent internalizing symptoms and polysubstance use: Gender comparisons. Journal of Youth and Adolescence, 36(6), 725–740. https://doi.org/10.1007/s10964-007-9179-1

Type of Study: Randomized controlled trial
Number of Participants: 383 families

Population:

• Age — Children: 6th grade at baseline; Parents: Mean=37.7–40.2 years
• Race/Ethnicity — Children: Not specified; Parents: 99% White
• Gender — Children: 53% Female; Parents: Not specified
• Status — Participants were parents and their 6th grade children.

Location/Institution: Twenty-two rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (2004). The purpose of the study was to evaluate the effects of the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] on growth patterns of adolescent internalizing (anxiety and depressive symptoms) and monthly polysubstance use (alcohol, tobacco, marijuana, inhalants, and other illicit drugs), as well as the association between internalizing and polysubstance growth factors. Schools were randomly assigned to one of two experimental conditions: ISFP or a minimal-contact control condition. Measures utilized include the Child Behavior Checklist—Youth Self Report (CBCL-YSR) and self-report of past month substance use. Results indicate that compared to the control group, the ISFP adolescents showed a slower rate of increase in internalizing symptoms and polysubstance use. Intervention effects on internalizing symptoms were similar for boys and girls; however, girls demonstrated a higher overall level and a greater rate of increase across time. ISFP slowed the rate of increase in polysubstance use significantly more for girls than for boys, although overall levels of use were lower in the intervention group for both genders. Associations between internalizing and polysubstance use growth factors were found for girls, but not for boys, suggesting gender differences in psychosocial development. Limitations include reliance on self-report measures, lack of generalizability of results to nonrural and more ethnically diverse populations, differences in the measurement recall timeframes, and that the sample size precluded some analyses.

Length of controlled postintervention follow-up: Approximately 6 years.

Spoth, R. L., Randall, G. K., Trudeau, L., Shin, C., & Redmond, C. (2008). Substance use outcomes 5½ years past baseline for partnership-based, family-school preventive interventions. Drug and Alcohol Dependence, 96(1–2), 57–68. https://doi.org/10.1016/j.drugalcdep.2008.01.023

Type of Study: Randomized controlled trial
Number of Participants: 1,677

Population:

• Age — 7th grade at baseline
• Race/Ethnicity — 96% White
• Gender — 53% Male
• Status — Participants were 7th grade students.

Location/Institution: Thirty-six rural schools in 22 contiguous counties in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (2005). The purpose of the study was to report adolescent substance use outcomes of universal family and school preventive interventions 5½ years past baseline. Schools were randomly assigned to (a) a classroom-based LST + Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14), (b) LST, or (c) a control condition. Self-reports were collected at baseline, 6 months later following the interventions, then yearly through the 12th grade. Measures utilized include initiation—alcohol, cigarette, marijuana, and drunkenness, along with a Substance Initiation Index (SII)—and measures of more serious use—frequency of alcohol, cigarette, and marijuana use, drunkenness frequency, monthly poly-substance use, and advanced poly-substance use. Results indicate that, for all substance initiation outcomes, one or both intervention groups showed significant positive point-in-time differences at 12th grade and/or significant growth trajectory outcomes when compared with the control group. Although no main effects for the more serious substance use outcomes were observed, a higher-risk subsample demonstrated significant positive 12th grade point-in-time and/or growth trajectory outcomes for one or both intervention groups on all measures. The observed pattern of results likely reflects a combination of predispositions of the higher-risk subsample, the timing of the interventions, and baseline differences between experimental conditions favoring the control group. Limitations include lack of generalizability due to population sample, and reliance on self-reported measures.

Length of controlled postintervention follow-up: Approximately 5 years.

Spoth, R., Trudeau, L., Shin, C., & Redmond, C. (2008). Long-term effects of universal preventive interventions on prescription drug misuse. Addiction, 103(7), 1160–1168. https://doi.org/10.1111/j.1360-0443.2008.02160.x

Type of Study: Randomized controlled trial
Number of Participants: Study 1: 667; Study 2: 2,127

Population:

• Age — Study 1 & 2: 17–21 years at follow-up
• Race/Ethnicity — Study 1: 98% White; Study 2: 99% White
• Gender — Not specified
• Status — Study 1: Participants were 6th grade students at study enrollment; Study 2: Participants were 7th grade students at study enrollment.

Location/Institution: Rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999), and Spoth et al. (2006). The purpose of the study was to examine the long-term effects of universal preventive interventions conducted during middle school on 17–21-year-olds’ prescription drug misuse. Two randomized controlled prevention trials were conducted in public schools in the rural Midwestern United States. In study 1, schools were assigned to the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)], Preparing for the Drug Free Years, or a control condition. In study 2, schools were assigned to the school-based Life Skills Training (LST) plus SFP 10–14 (LST + SFP 10–14), LST-only, or a control condition. Measures utilized include self-reports of lifetime and past-year prescription drug misuse. Results indicate that in study 1, ISFP 12th-graders’ past year narcotic misuse was significantly less than controls, as were ISFP 21-year-olds’ life-time narcotic and barbiturate misuse rates. In study 2, LST + SFP 10–14 showed significant effects on life-time prescription drug misuse at the 11th-grade follow-up, while effects at the 12th-grade follow-up were marginally significant. Limitations include lack of generalizability to nonrural populations, rural populations in other regions of the country, or populations with different ethnic compositions; limited numbers of methamphetamine users in the sample; and concerns regarding potential bias due to school effects.

Length of controlled postintervention follow-up: Approximately 6 and 9 years.

Spoth, R. L., Trudeau, L., Guyll, M., Shin, C., & Redmond, C. (2009). Universal intervention effects on substance use among young adults mediated by delayed adolescent substance initiation. Journal of Consulting and Clinical Psychology, 77(4), 620–632. https://doi.org/10.1037/a0016029

Type of Study: Randomized controlled trial
Number of Participants: 667 families

Population:

• Age — Children: Mean=11.3 years; Parents: Mean=37.3– 40.1 years
• Race/Ethnicity — Children: Not specified; 99% Caucasian
• Gender — Children: 51% Female; Parents: Not specified
• Status — Participants were 6th graders and their families.

Location/Institution: Thirty-three rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999). The purpose of the study was to examine whether delayed substance initiation during adolescence, achieved through Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] and Preparing for the Drug Free Years program (PDFY) conducted in middle school, can reduce problematic substance use during young adulthood. Schools were randomly assigned to three experimental conditions: those receiving the seven-session ISFP, the five-session PDFY, or a minimal-contact control condition. Measures utilized include the Rutgers Alcohol Problems Index as well as questionnaires regarding tobacco, and other illicit drug use. Results indicate that the models fit the data and that they were robust across outcomes and interventions, with more robust effects found for ISFP. The addition of direct intervention effects on young adult outcomes was not supported, suggesting long-term effects were primarily indirect. Relative reduction rates were calculated to quantify intervention-control differences on the estimated proportion of young adults indicating problematic substance use that was higher for ISFP than for PDFY. Limitations include reliance on self-report measures, attrition, and lack of generalizability of results to nonrural and more ethnically diverse populations.

Length of controlled postintervention follow-up: Approximately 10 years.

Spoth, R., Guyll, M., & Shin, C. (2009). Universal intervention as a protective shield against exposure to substance use: Long-term outcomes and public health significance. American Journal of Public Health, 99(11), 2026–2033. https://doi.org/10.2105/AJPH.2007.133298

Type of Study: Randomized controlled trial
Number of Participants: 446 families

Population:

• Age — Not specified
• Race/Ethnicity — Families: 98% Caucasian
• Gender — Not specified
• Status — Participants were 6th graders and their families

Location/Institution: Twenty-two rural schools in a Midwestern state

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999). The purpose of the study was to examine the effects of the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] on adolescents’ exposure to opportunities for substance use and on illicit substance use in the long term. Public schools were randomly assigned to the ISFP or a control condition. Measures utilized include the National Survey on Drug Use and Health. Results indicate that ISFP was associated with reduced exposure to illicit substance use that was, in turn, associated with reduced 12th-grade substance use. The ISFP also reduced the rate of increase in exposure across adolescence, which was associated with the likelihood of 12th-grade illicit substance use, with a significant indirect effect. Limitations include reliance on self-report measures, data from PDFY was omitted, and lack of generalizability of results to nonrural and more ethnically diverse populations.

Length of controlled postintervention follow-up: Approximately 6 years.

Spoth, R., Trudeau, L., Shin, C., Ralston, E., Redmond, C., Greenberg, M., & Feinberg, M. (2013). Longitudinal effects of universal preventive intervention on prescription drug misuse: Three randomized controlled trials with late adolescents and young adults. American Journal of Public Health, 103(4), 665–672. https://doi.org/10.2105/AJPH.2012.301209

Type of Study: Randomized controlled trial
Number of Participants: Study 1: 446 families; Study 2 & Study 3: Not specified

Population:

• Age — Study 1: Mean=11.32–11.34 years; Study 2: Mean=12.77–12.78 years; Study 3: Mean=11.82–11.85 years
• Race/Ethnicity — 98% White (Study 1); Not specified for studies 2 and 3
• Gender — Study 1: 48% Male; Study 2: 53% Male; Study 3: 50% Male
• Status — Participants were 6th or 7th grade students at baseline.

Location/Institution: Rural communities in the United States

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999) and Spoth et al. (2002). The purpose of the study was to examine long-term prescription drug misuse outcomes in 3 randomized controlled trials evaluating brief universal preventive interventions conducted during middle school. Study 1, initiated in 1993, tested a family-focused intervention alone; study 2, initiated in 1998, tested a combination of a family-focused and a school-based intervention; Study 3, initiated in 2002, was designed to examine a delivery system for evidence-based universal family focused and school-based interventions selected from a menu. The following interventions were tested: the Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)]; a revised ISFP, the Strengthening Families Program: For Parents and Youth 10–14 plus the school-based Life Skills Training (SFP 10–14 + LST); and the SFP 10–14. Measures utilized include self-reported outcomes of prescription opioid misuse (POM) and lifetime prescription drug misuse overall (PDMO). Results indicate that ISFP showed significant effects on POM and PDMO, relative reduction rates (RRRs; age 25 years) of 65%, and comparable benefits for higher- and lower-risk subgroups. SFP 10–14 + LST showed significant or marginally significant effects on POM and PDMO across all ages (21, 22, and 25 years); higher-risk participants showed stronger effects (RRRs =32%–79%). Significant results were found for POM and PDMO (12th grade RRRs = 20%–21%); higher-risk and lower-risk participants showed comparable outcomes. Limitations include findings may not generalize to populations with different geographic (e.g., suburban, urban) or ethnic compositions.

Length of controlled postintervention follow-up: Study 1: at age 25 (approx. 13 years). Studies 2 & 3: Not specified.

Spoth, R., Trudeau, L., Shin, C., Randall, G. K., & Mason, W. A. (2019). Testing a model of universal prevention effects on adolescent relationships and marijuana use as pathways to young adult outcomes. Journal of Youth and Adolescence, 48(3), 444–458. https://doi.org/10.1007/s10964-018-0946-y

Type of Study: Randomized controlled trial
Number of Participants: 446 families

Population:

• Age — 10–13 years (Mean=11.3 years)
• Race/Ethnicity — 98% Caucasian
• Gender — 48% Male
• Status — Participants were 6th graders and their families.

Location/Institution: Twenty-two Iowa schools

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as Spoth et al. (1999). The purpose of the study was to use data from a randomized controlled trial to test a longitudinal, developmental model Positing Pathways of Iowa Strengthening Families Program (ISFP) [now called Strengthening Families Program: For Parents and Youth 10–14 (SFP 10–14)] effects on age 21 illicit drug use and positive relationship affect, via earlier effects on adolescent relationships and marijuana use. Participants were randomly assigned to the ISFP or a control group. Measures utilized include the Positive Youth Development Student Questionnaire, Short version, the Job Satisfaction Survey, middle-school relationships (parents, peers, school), high school marijuana use, plus age 21 illicit drug use and relationship affect (parents, work, school), 10 years past intervention implementation. Results indicate that intervention effects on young adult variables were indirect, through effects on adolescent outcomes, with higher-risk participants showing greater intervention impact. Limitations include reliance on self-report measures, small sample size in the high-risk group, and lack of generalizability of results to nonrural and more ethnically diverse populations.

Length of controlled postintervention follow-up: Approximately 10 years.