Criminal recidivism in mentally ill offenders, In the context of a county jail, has not been extensively studied. This study compares the rate of criminal recidivism between those who suffered from a mental illness at the time of arrest and those who did not. In addition, the length of incarceration between these two groups was compared. Using survival analysis, a risk assessment model describing the key features involved in criminal recidivism among the mentally ill may be built. To our knowledge, this study is the first of its kind and will suggest areas of intervention that could prevent criminal recidivism among mentally ill offenders. Due to the lack of literature on the subject, this pilot study provides estimates of key parameters, such as types of crimes and frequency of incarceration, needed to undertake a definitive study. Furthermore, the pilot study provides an opportunity to develop and field test a data abstraction form and computer matching methods.