This issue consists of five articles profiling different aspects of the national evaluation of the Comprehensive Community Mental Health Services for Children and Their Families Program. Over the last eight years, this program provided grants to develop community-based systems of care for children with serious emotional disturbance and their families. A comprehensive, multilevel evaluation has been conducted that has provided information to local grantee communities and the federal government on the implementation and effectiveness of systems of care. Touching on a range of questions that the evaluation is designed to address, the articles in this special issue provide more general information on the system-of-care approach to addressing children's mental health problems.