Research suggests that well-developed parent engagement programs can boost early learning and reduce socioeconomic disparities in subsequent school adjustment. Yet few follow-up studies exist. To address this gap, we followed participants in the Research-based, Developmentally Informed-Parent [REDI-P] intervention study for 8 years to evaluate adolescent outcomes. Participants included 200 4-year-old children (55% White, 26% Black, 19% Latinx; 56% male, 44% female; Mage at study entry = 4.45 years) attending Head Start. Families were randomly assigned to REDI-P home learning materials and coaching or an attention control group. Multi-method measures tracked child literacy skills, learning behaviors, social competence, and conduct problems through grade 7. GLM analyses revealed significant preschool intervention effects on grade 7 working memory, β = 0.35, 95% CI 0.08, 0.62, p = .01; perceived social competence, β = 0.30, 95% CI 0.02, .58, p = .04; deviant peer affiliation, β = −0.33, 95% CI −0.60, −0.06, p = .02; and teacher-rated conduct problems, β = −0.30, 95% CI −0.58, −0.01, p = .04. Serial path models identified developmental progressions linking initial intervention effects to adolescent outcomes. Results highlight the long-term value of empowering parents to support the early social-emotional and pre-academic learning of their preschool children.