The federal Comprehensive Community Mental Health Services for Children and Their Families Program was initiated in 1992 to provide grants to states, communities, territories, and Indian tribes to develop systems of care to serve children and adolescents with or at risk for emotional disorders and their families. As part of the national evaluation of this program, a study was undertaken to assess the ability of funded sites to sustain their systems of care beyond the federal grant period. The study involved a web survey and telephone interviews with local and state respondents to examine the extent to which key components of systems of care were maintained during the period in which federal funds were phasing out and during the post grant period. Study results demonstrate positive and negative changes that occurred in the communities which are included in the sample, with respect to maintaining the availability of each service included in the broad service array, the implementation of system of care principles, the system of care infrastructure, and the achievement of system of care goals. In addition, results identify factors that contribute to or impede the ability to sustain systems of care, and the effectiveness of various strategies for sustainability. Study findings offer guidance not only to federally funded system of care communities but also to non-funded communities engaged in system of care development to enhance their ability to sustain systems of care for this population over time. Findings will also assist federal, state, and local policymakers, technical assistance providers, family members, advocates, and other key stakeholders to more effectively support the development of viable, sustainable systems of care.