Community psychiatric nurses [CPN] have been described as probably the most important single professional in the process of moving care of mental illness into the community. However, detailed information about their development was not available and the central source of information was known to be unreliable. This study was undertaken to improve the quality of information available related to the contemporary circumstance of community psychiatric nursing in the United Kingdom. From a range of baselines and at differential speeds, evidential data has been provided to trace the growth and the continued movement of the CPN workforce away from its original sources of referral and away from its original clientele and original operational base, toward a closer identification with primary health care providers, their clientele and their workplaces. Such shifts have been associated with concomitant changes to the shape and nature of CPN service provision over time. A range of arguments have been offered to explain such movements. After four decades of unfettered local development, recent policy initiatives have interrupted the direction of CPN Service growth. Such an interruption has served to force a fundamental reconsideration of the level and balance of local service provision and of different educational preparations. This thesis has argued that these policy priorities have located themselves both within an historical context and a contemporary setting, and will force a realignment of CPN service delivery in favour the interests of seriously mentally ill people. This will compel community psychiatric nurses to return to closer working practices with their original sources of referral and return them to their original clientele, if not their original operational bases. This will require the nature of CPN relationships to be re-configured to accommodate the impact these changes will have on other nursing-based groups in primary health care settings, where a different set of roles will need to established. Thus, community psychiatric nurses will have to review and reconcile the definition of their roles to the changes in the fast-changing National Health Service. This will be a necessary, but not sufficient, condition to achieve the potential advantages to client care which are envisaged by the Reforms. Rather, these will become vital matters for all professional groups involved in community mental health care provision to address and accommodate, within their structural interests as stakeholders, in negotiation not only with one with another, but with service users.