Findings and methodology are presented for an evaluation of Raising Healthy Children (RHC), a preventive intervention designed to promote positive youth development by targeting developmentally appropriate risk and protective factors, with a focus on reducing adolescent alcohol, marijuana, and cigarette use.
A total of 959 1st- and 2nd-grade students (54 percent male students, 18 percent minority, 28 percent low socioeconomic status) in 10 public schools were matched and assigned randomly to either intervention or control conditions. A two-part latent growth modeling strategy was used to examine change in both use-versus-nonuse and frequency-of-use outcomes while students were in grades 6-10. Results indicated significant (p < .05) intervention effects in growth trajectories for frequency of alcohol and marijuana use but not for use versus nonuse. These findings provide support for preventive interventions that take a social development perspective in targeting empirically supported risk and protective factors and demonstrate the use of two-part models in adolescent substance-use research. (publisher abstract modified)