This study examines long-term effects of a transition to parenthood program, Family Foundations, designed to enhance child outcomes through a strategic focus on supporting the coparenting relationship. Roughly 5 to 7 years after baseline (pregnancy), parent and teacher reports of internalizing and externalizing problems and school adjustment were collected by mail for 98 children born to couples enrolled in the randomized trial. Teachers reported significantly lower levels of internalizing problems among children in the intervention group compared with children in the control group and, consistent with prior findings at age 3, lower levels of externalizing problems for boys in the intervention group. Baseline level of observed couple negative communication moderated intervention effects for parent and teacher report of child adjustment and teacher report of school adjustment and adaptation. Effect sizes ranged from 0.40 to 0.98. Results indicate that relatively brief preventive programs for couples at the transition to parenthood have the capacity to promote long-term positive benefits for children’s adjustment. Although we attended to missing data issues in several ways, high levels of attrition in this long-term follow-up study is a cause for caution.