This study compared intensive case management (ICM) with standard clinical case management in a well-resourced community mental health service in Australia. A total of 73 severely disabled clients of an existing clinical service were randomly allocated to either ICM (caseload 10 clients per clinician) or standard case management (caseload up to 30 clients per clinician) and followed up for 12 months. A greater proportion of clients receiving ICM showed improved social functioning, these clients had fewer psychiatric hospital admissions involving police, and were more likely to engage and remain in treatment compared to those who received standard case management. Clients receiving ICM did not show a reduction in hospitalization duration or total number of episodes. It is suggested that future studies of ICM should focus on which aspects of treatment produce positive outcomes, how they can be applied to routine clinical settings, and over what period of time outcomes are sustained.