Commissioned by the Home Office Police Resources Unit, this study assists in meeting the government’s target to increase police numbers. The study attempted to fill a gap in knowledge about the reasons for transfer and resignation and to inform the development of effective and practical retention initiatives. The study collected information on officers who left the service voluntarily and identified patterns in the wastage and mobility of officers and attempted to understand the factors influencing these patterns. Ten police forces took part in the study, 6 with high levels of resignations and transfers and 4 with lower levels. Study findings include: (1) police service has increasing rates of resignation and mobility, but the rates remain below those of other public service; (2) common concerns among those leavings were the variety of police work was important in attracting officers and remained a source of satisfaction for many leavers and management was perceived as unfair and ineffective at all levels; (3) many transferers were concerned about improving their quality of life; (4) there were higher rates of transfer and resignation from forces in the south-east of England; (5) minority ethnic resigners were more likely to have fewer years of service and to be older than other resigners; (6) reasons for women resigning from the force were similar to men’s, except they were more likely to leave the force because of domestic responsibilities; and (7) many of those who resigned as probationers said that they felt isolated and lacked support. Four major recommendations were presented and included: (1) improve management; (2) build on the positive aspects of working in the force; (3) look at the impact of area initiatives; and (4) address the challenges facing particular groups in the service. Tables, figures, and appendix