The high rates of dropping out and other engagement problems are significant concerns in the delivery of mental health and adjunct services to the families of at-risk children. Consequently, researchers have examined the correlates of attrition and have developed interventions to increase engagement and retention. However, the lack of a clear definition of engagement and gaps in theory about the relationship of engagement to other treatment processes hinder knowledge development. In this paper the behavioral and attitudinal aspects of engagement are disentangled. Current knowledge about treatment barriers and interventions to increase appointment keeping is summarized. A preliminary conceptualization of the engagement process is presented and research needs and practice implications are discussed.