The effects of service expansion and change (including Joint working with social services) following the provision of a community mental health centre and the introduction of care management were examined by auditing service activity. Data were collected on service provision to 20 randomly selected patients who met the local criteria for care management, and also on the general level of service activity as judged by service contacts for all disciplines. Compared to the baseline period, face to face contact with care-managed patients increased six-fold. There were more home contacts, a wider range of professional contacts occurred, and a greater variety of types of treatment provided. A substantial (though not statistically significant) reduction in day hospital attendance was seen over the period studied. The number of service contacts for non-care-managed patients also rose. The introduction of care management was simplified by changes in service organisation. Increased resources were needed to both implement care management and provide an adequate service to the remainder of patients. Both aspects of the service functioned efficiently in parallel.