A look at the main critical theories of the 20th century and their relevance and potential applications in social work. Among the theories: Marxism and its relevance to radical social work; Neo-Marxism (Pierre Bourdieu) and its relevance for new public management; Post-structuralism (Foucault) and an analysis of social work as discourse and as a regime of truth; Feminisms, a gender analysis of social problems and feminist activism in social work; Post-Colonialism and critical analysis of multi-cultural social work.