Separating systems, such as mental health, social services, and law enforcement can undermine policy efforts to organize these pieces around the whole person. To build a system that works for mentally disordered offenders entails understanding what does not work and what causes dysfunction and then building an integrated system that works for the whole. This paper is the first of a two-part series which examines alternative approaches to integrating services for mentally disordered offenders. The analysis begins by reviewing the evidence in Britain of systems and services dysfunction as it relates to mentally disordered offenders to establish the need for the integration of systems and the integration of services. The analysis concludes by exploring three identified barriers associated with achieving services and systems integration: (1) funding fragmentation; (2) resource allocation or inadequate and inconsistent funding; and (3) bureaucratic inflexibility; and draws on experiences in the United States and the United Kingdom to overcome these barriers. Part two of this series will present a “new” holistic approach to integrating services for mentally disordered offenders. References