Early intervention will be successful only when services are coordinated across agencies and sectors. This article briefly reviews the barriers to interagency coordination as outlined in the literature and then presents results of a 2-year case study. A synthesis of data collected from six diverse states revealed that agencies are qualitatively and fundamentally different from one another in many crucial aspects. This article presents 13 ways that public agencies differ from one another and provides a set of recommendations to assist diverse agencies in coming together to develop a comprehensive and coordinated system of services. Key words: collaboration, cooperation, coordination, interagency, interdisciplinary, service integration, systems