Historically, as many as 7–10% of US police contacts have involved persons with mental illnesses, with a disproportionate amount of these encounters resulting in arrest, usually for minor offenses. Crisis Intervention Teams (CIT) were created, and have proliferated, to ameliorate this problem by offering a specialized response and serving – at least informally – as a liaison between mental health services and police departments. Because preventing unnecessary arrests is one of CIT’s principal objectives, this study examined the arrest rates of persons with mental illnesses and the number of arrests that might have been prevented after the implementation of a CIT program in a large county in Central Florida. The arrest rate after CIT implementation was found to be very low and even declined across time providing evidence that CIT programs may indeed be useful in reducing discretionary arrests among persons with mental illnesses.