Police agencies across the country are struggling to respond to significant number of persons with serious mental illness, who are landing on their doorsteps with sometimes tragic consequences. Arguably, the most widely adopted approach, the Crisis Intervention Team (CIT) model, is a specialized police-based program designed to improve officers' ability to safely and effectively respond to mental health crises. Conducting research on CIT is challenging; thus, the evidence base is limited. In this article, the author reviews the emerging literature, present a conceptual model of CIT effectiveness, and describe a study of CIT in Chicago. Findings from Chicago suggest that CIT is increasing linkage to services and reducing use of force in encounters with persons with mental illness. Lessons learned are discussed. (Contains 1 figure.)