Since 2000 assertive outreach has been a requirement of community mental health provision in the UK. This has led to rapid proliferation of assertive community treatment teams offering a pure form of clinical case management to people with severe mental illness. The teams provide intensive support in obtaining material essentials such as food and shelter and place a greater emphasis on social functioning and quality of life than on symptoms. People with psychotic illness with fluctuating mental state and social functioning and poor medication adherence are most likely to benefit. Teams are ideally placed to monitor clozapine treatment in the community. Teams require a broad skills mix, and team members need some competence across a wide range of areas. Teams should include a psychiatrist or have regular access to one. Ideal individual case-loads are 10–12 patients. Around-the-clock availability is no longer considered essential, particularly in view of the rise of crisis resolution/home treatment teams.