This document discusses several theories and approaches to case work practice, including psychosocial approach, problem solving approach, crisis intervention, behaviour modification, and functional approach. It provides details on each approach, including their origins, key principles, stages or phases of practice, assessment methods, treatment principles and goals. The psychosocial approach views the client in their social situation and addresses both interpersonal relationships and personality. Behaviour modification aims to increase desired behaviours and decrease undesired behaviours through techniques like positive reinforcement. The functional approach focuses on understanding the client's situation and using agency resources and the worker-client relationship to facilitate change.