Experimental studies of assertive community treatment programs based on the Training in Community Living model are reviewed. In most of the programs studied, interdisciplinary treatment teams met with patients in the community, taught them to take care of basic needs, and ensured that they received adequate material support and medical care. Across the service settings and patient populations studied, assertive community treatment reduced hospital utilization. Although early researchers provided evidence that the approach was more effective than conventional treatment in controlling symptoms, promoting social functioning, and improving occupational performance, recent studies have generally not replicated these findings. Defining the conditions under which assertive community treatment achieves superior functional outcomes remains an important challenge for future research.