The authors evaluate the relation of ethnic, socioeconomic status (SES), and belief match between parents and group leaders and engagement in a preventive intervention for parents of preschoolers. Engagement was assessed through attendance, retention, and quality of participation in sessions with 171 parents and 11 group leaders. SES match predicted attendance, retention, and quality of participation. Parents attended more sessions, remained longer in the program, and participated more actively when their group leader came from comparable SES backgrounds. Ethnic match predicted retention only, with parents attending longer when their ethnicity matched their group leader's. Engagement was unrelated to the extent of match across different characteristics, nor was the link between ethnic match and retention mediated by SES or belief match. Results suggest that social, cultural, and belief similarities between parents and group leaders may be less salient in preventive parenting interventions than is assumed. Implications for research and practice are discussed. (Contains 2 tables.)