This scoping review examined the literature on decision making by practitioners in the social professions involved in compulsory admission to mental health hospital in the UK. This aimed to find out(i) what processes shape social profession decision making about compulsory admission to mental health hospitals in practice? and (ii) what methods have informed studies in this area, and how have these shaped the current state of knowledge?Three main themes emerged are: professional positioning; characteristics of the person assessed; and organisational factors. The literature has approached answering this question by focusing on social professional jurisdictional perspectives, emphasising concern whether a social perspective is privileged in decision making. Lack of realistic options to avoid in-patient care underpins decisions to detain. The process involves a logistical challenge for the social profession. The social milieu of those assessed is associated with social vulnerability and social deprivation, highlighting the relevance for social work. Concerns about risk and a citizen’s lack of mental capacity to make decisions about care are associated with decisions to detain. Implications for social work include a need for research that explores the institutional and social context of decision making. Finally, implementing supported decision making in social work practice is proposed as an imperative for future research.