A new measure, Continuity of Care in Children’s Mental Health (C3MH), is presented. The study involved item generation, pre-testing, pilot testing, and validation. The C3MH was administered to 364 parents recruited from 13 children’s mental health agencies in Ontario, Canada. The measure includes five scales supported by confirmatory factor analysis. Scale validity was supported through analyses of relationships with established measures of satisfaction, problem severity, and therapeutic alliance, as well as through known-group differences. The results of a pilot youth-report version (N = 57) are presented. The C3MH will be a useful tool for assessing improvements in system integration.