Most mental health problems begin in childhood and adolescence, but delays in receipt of treatment are measured in years to decades. As a result, mental health problems cause a disproportionate burden of disability among children and youth compared to adults, and have a major impact on life course development. Primary care services can play an important role in efforts to prevent and intervene early in the course of child and adolescent mental health problems. Primary care services are widely available and offer an opportunity to interact simultaneously with children and their parents, treat mental health in the context of medical and developmental concerns, and reduce the stigma associated with visiting identifiable mental health facilities. While research with adults has shown the feasibility of integrating mental health care into primary care settings, and that it reduces the burden of mental illnesses, there have been few studies among children and youth and none that address a combined task-shifting/stepped care model. In addition, evidence remains lacking that integration is feasible in diverse settings, that it improves clinical outcomes, and has the potential to be scaled up.