This chapter investigates critical criminology. The strands that are widely regarded as most important in the development of critical criminology are labelling perspectives, Marxist-inspired critical theories, power perspectives, and feminist perspectives. The ideas and insights contained within these theories inspired and prepared the ground for more recent developments in the field, including cultural criminology and convict criminology. Critical criminology not only suggests that we make small alterations to criminal justice systems; instead, it requires us to question everything we think we ‘know’ about these systems and the societies and communities in which we live. It questions how and why we control behaviour, looks at power from the perspective of the oppressed or the powerless, and suggests alternative narratives that should be part of our accepted knowledge base.