This study aimed to analyze nursing workers' concepts on the purpose, object and tools used to provide care to psychotic patients in a Psychosocial Community Center--III, Brazil. This qualitative, descriptive and exploratory study used document research, participant observation and interviews. Results reveal diverse concepts regarding the purposes and characteristics of the object, linked to the knowledge each concept is based on. We observed that the first is inspired on Care, Psychosocial Rehabilitation and Psychoanalysis; the second re-signifies principles of Rehabilitation and recovers aspects of moral treatment, and the third translates the idea of professional core and field. We conclude that there is a need for investments in the production of a conceptual corpus and practices that permit changing workers' position on the production of services at CAPS.17368-73