Including fathers is the next frontier for infant mental health. In this article, the authors describe the inclusion of fathers as equal partners in Child-Parent Psychotherapy (CPP), an evidence-based treatment for young children experiencing or at risk for mental health problems following exposure to violence and other adversities. The authors present two vignettes in which the father's participation in treatment was pivotal to successful outcomes for the child, and they illustrate some of the considerations, complexities, concerns, and rewards of engaging and working with fathers. They discuss the benefit of using a "triadic lens" (McHale, 2011) for formulation and treatment planning with all families involved with CPP.