The term ‘policing’ is often used to refer to a broad range of regulatory practices, which have been associated with the development of educative and social work frameworks in the modern state. The relationship between the concepts of ‘welfare’ and ‘penality’ (or ‘care’ and ‘control’) has been the subject of a number of recent studies of social intervention in twentieth-century Britain. However, the role of police officers themselves in the ‘policing of families’ has rarely been elaborated. From their initial appointment to London's Metropolitan Police in 1919 until their official integration on the same terms as male officers in the early 1970s, women police officers played a significant role in the detection and prevention of child abuse, neglect, and female delinquency. Through a case study of the work of the Metropolitan Women Police branch, this article considers the negotiation of a social work ethic within policing as well as the shifting configuration of the ‘care’/‘control’ nexus in welfare legislation and professional practice. The Metropolitan Women Police tended to see ‘care’ and ‘control’ as mutually reinforcing rather than conflicting concepts. Such a formulation was resonant with the rhetoric of social work and official legislation until the early 1960s. It also reflected the philosophy of crime prevention laid down as the principal object of policing, enabling women to justify involvement in child protection and welfare as an aspect of police work.