This paper reports the results of a 10-year follow-up of two variations of a couplesʼ group preventive intervention offered to couples in the year before their oldest child made the transition to kindergarten. One hundred couples were randomly assigned to (1) a low-dose control condition, (2) a couplesʼ group meeting for 16 weeks that focused more on couple relationship issues among other family topics, or (3) a couplesʼ group meeting for 16 weeks that focused more on parenting issues among other family issues, with an identical curriculum to condition (2). Earlier papers reported that both variations of the intervention produced positive results on parent-child relationships and on the childrenʼs adaptation to kindergarten and first grade, and that the groups emphasizing couple relationships also had additional positive effects on couple interaction quality. The present paper uses growth curve analyses to examine intervention effects extending from the childrenʼs transition to kindergarten to the transition to high school—10 years after the couples groups ended. There were 6-year positive effects of the pre-kindergarten interventions on observed couple interaction and 10-year positive effects on both parentsʼ marital satisfaction and the childrenʼs adaptation (hyperactivity and aggression). Discussion includes a focus on the implications of these results for family policy, clinical practice, and the need to include a couples focus in preventive interventions to strengthen family relationships and enhance childrenʼs adaptation to school.