Children with serious mental or emotional disorders require a range of services and supports, as do their families. Yet fragmentation of services and conflicting program rules have long impeded children's and families' access to needed care. This issue brief examines how federal programs and rules have contributed to this fragmentation and explores ways to harmonize some of the differences between them so as to foster coordination of the services and supports needed by each child and family. In addition to funding a range of categorical programs, the federal government, through the Center on Mental Health Services, the Maternal and Child Health Bureau and other agencies, promotes a systems-of-care approach. Systems of care require the major child-serving agencies to collaborate in order to ensure that each child and family has a single plan of care detailing services to be provided and that these services are funded in a coordinated way. Target populations for these systems of care vary at the state and local level. Some focus on children with serious mental disorders and others on a broader group of children. This issue brief focuses on the needs of children with mental disorders within a system of care, regardless of the population of children included within that system. (GCP)