This parameter presents overarching principles and practices for child and adolescent mental health care in community systems of care. Community systems of care are defined broadly as comprising the wide array of child-serving agencies, programs, and practitioners (both public and private), in addition to natural community supports such as religious and consumer organizations. Recommended principles and practices are derived from the system-of-care approach to service delivery. Based on the principles of the Child and Adolescent Service System Program, this approach has had a major influence on community systems of care through extensive federally funded projects and initiatives. The system-of-care model emphasizes that care should be tailored to the individual needs and strengths of the child and family and provided in the most community-based and least restrictive setting that meets their needs. Families are included as partners in the clinical process and are also involved in program development and evaluation. Services are coordinated and integrated into a comprehensive care plan. This model can be practiced even in the absence of formal systems of care or protocols, with the individual clinician promoting interagency coordination and child and family collaboration. This parameter is written for a broad audience of mental health professionals, with special emphasis on the roles of child and adolescent psychiatrists in community systems of care.