An expanding body of research suggests an important role for parent or family competency training in children's social-emotional learning and related school success. This article summarizes a test of a longitudinal model examining partnership-based family competency training effects on academic success in a general population. Specifically, it examines indirect effects of the Iowa Strengthening Families Program (ISFP) on school engagement in 8th grade and academic success in the 12th grade, through direct ISFP effects on intervention-targeted outcomes--parenting competencies and student substance-related risk--in 6th grade. Twenty-two rural schools were randomly assigned to either ISFP or a minimal-contact control group; data were collected from 445 families. Following examination of the equivalence of the measurement model across group and time, a structural equation modeling approach was used to test the hypothesized model and corresponding hypothesized structural paths. Significant effects of the ISFP were found on proximal intervention outcomes, intermediate school engagement, and the academic success of high school seniors. (Contains 2 figures and 3 tables.)