The Comer School Development Program (SDP) has received considerable national attention over the last decade. The authors describe the origins, central tenets, and principles of the SDP. Although the Comer model is a systemic one, one of its primary foci is the developmental and mental health needs of children attending urban schools. The authors illustrate how teaching and consulting school faculty and parents about basic principles of development and psychopathology change the interaction between the child and adults who are important to the child. The authors contend that this step is an essential prerequisite for effective evaluation and treatment of children with possible psychiatric disturbances.