Engaging and retaining families in mental health prevention and intervention programs is critically important to insure maximum public health impact. We evaluated randomized-controlled trials testing methods to improve family engagement and retention in child mental health programs published since 1980 (N = 17). Brief, intensive engagement interventions in which providers explicitly addressed families’ practical (e.g. schedules, transportation) and psychological (e.g. family members’ resistance, beliefs about the treatment process) barriers as they entered treatment were effective in improving engagement in early sessions. The few interventions found to produce long-term impact on engagement and retention integrated motivational interviewing, family systems, and enhanced family stress and coping support strategies at multiple points throughout treatment. Few interventions have been tested in the context of prevention programs. There are promising approaches to increasing engagement and retention; they should be replicated and used as a foundation for future research in this area.