This paper is an overview of the conceptual and methodological problems encountered trying to assess the hypothesis that the mentally ill, as a consequence of deinstitutionalization, are being "criminalized". Generalizations are difficult to make, in large part because most of the studies are American and do not fit well into the Canadian scene. Relevant Canadian findings are reviewed and compared to the US data. There is some evidence that Canadian patients may be diverted from the criminal justice system more often than in the US, where there are fewer resources. However, this conclusion must be tempered by the fact that Canadian surveys have found high rates of mental disorder among prison and jail inmates.