A variety of predictors of parent participation in prevention programming have been identified in past research, but few studies have investigated how those predictors may vary by implementation context. Patterns of parent participation were examined in the Early Risers Conduct Problems Prevention Program using two family-focused service delivery models: a community center model (Center) and an in-home outreach-based model (Outreach). An ethnically diverse sample of Kindergarten through second grade students (n = 246) displaying elevated levels of aggression were recruited for the study and randomly assigned to either the Center (n = 121) or Outreach (n = 125) models. In both delivery models, participants and their families completed an assortment of baseline measures and received family skills and child skills intervention components and family- and school-based case management. Parents in the Center model demonstrated greater overall participation in family-focused components of the intervention. Parent motivation with parent-focused expectancies for the intervention represented the strongest predictor of parent participation across both delivery models. Family income differentially predicted parent participation across the two models, with low income predicting greater participation in the Center model and lower participation in the Outreach model. A qualitative finding emerged showing that parents receiving parent skills in the Center model via groups preferred to learn skills related to facilitating overall family relationships, whereas parents receiving parent skills via individual Outreach meetings preferred to improve a child's behavior and emotion skills. Implications are discussed for the design of prevention programming in order to maximize parent participation in high risk populations.