Purpose. The paper provides an overview of the application of therapeutic community (TC) method in non-TC environments. Approach. Milieu treatment is defined and differentiated from TC 'proper'. Literature is reviewed covering attempts to use TC methods in inpatient wards, across hospitals, and more recently in the criminal justice system and more widely through the enabling environments initiative. Findings. It is unclear whether TC milieu treatments proved helpful in acute ward environments in their heyday in the 1950s, 60s and 70s, in particular those involving people suffering from acute psychosis, and the changing landscape of psychiatric provision may make further investigation difficult. The reasons for this, and for the difficulties reaching a firm conclusion, are outlined. In contrast, TC milieu interventions appear to be demonstrating usefulness more recently in less mixed populations without the implementation of full TC 'proper'. Limitations. Much of the original research is old and the methodology poor, which limits the conclusions that can be drawn. Practical implications. Recent innovations pick up in a more accessible way principles of therapeutic communities that can inform and improve care in a variety of contexts. They are sufficiently well defined to lend themselves to research, which should now be a priority.