The authors review the status, strength, and quality of evidence-based practice in child and adolescent mental health services. The definitional criteria that have been applied to the evidence base differ considerably across treatments, and these definitions circumscribe the range, depth, and extensionality of the evidence. The authors describe major dimensions that differentiate evidence-based practices for children from those for adults and summarize the status of the scientific literature on a range of service practices. The readiness of the child and adolescent evidence base for large-scale dissemination should be viewed with healthy skepticism until studies of the fit between empirically based treatments and the context of service delivery have been undertaken. Acceleration of the pace at which evidence-based practices can be more readily disseminated will require new models of development of clinical services that consider the practice setting in which the service is ultimately to be delivered.