Difficulty engaging families in mental health treatment is seen as an underlying reason for the disparity between child mental health need and service use. Interpretation of the literature on how best to engage families is complicated by a diversity of operational definitions of engagement outcomes and related interventions. Thus, we sought to review studies of engagement interventions using a structured methodology allowing for an aggregate summary of the most common practices associated with effective engagement interventions. We identified 344 articles through a combination of database search methods and recommendations from engagement research experts; 38 articles describing 40 studies met our inclusion criteria. Following coding methods described by Chorpita and Daleiden (J Consul Clin Psychol 77(3):566–579, 2009, doi:10.1037/a0014565), we identified 22 engagement practice elements from 89 study groups that examined or implemented family engagement strategies. Most frequently identified engagement practice elements included assessment, accessibility promotion, psychoeducation about services, homework assignment, and appointment reminders. Assessment and accessibility promotion were two practice elements present in at least 50 % of treatment groups that outperformed a control group in a randomized controlled trial. With the exception of appointment reminders, these frequently identified engagement practice elements had a high likelihood of being associated with winning treatments when they were used. This approach offers a novel way of summarizing the engagement literature and provides the foundation for enhancing clinical decision-making around treatment engagement.