New York State has had a mandatory incident reporting system in place since 1985. The current system, the New York Patient Occurrence Reporting and Tracking System (NYPORTS), was implemented in 1998 pursuant to New York State Public Health Law Section 2805-l, Incident Reporting. NYPORTS is a secure Web-based system that simplifies reporting, coordinates with other reporting systems, and allows hospitals to obtain feedback on their own reporting patterns. The authors review the evolution and implementation of NYPORTS and its predecessors, the Hospital Incident Reporting System and the Patient Event Tracking System. Discussion and data comparisons are made between the Joint Commission on Accreditation of Healthcare Organizations' voluntary sentinel event reporting system and NYPORTS. Critical elements for success of a mandatory incident reporting system include collaborative system design; basing the system on statute, with clear definitions and objective reporting criteria; providing meaningful data that can be analyzed and disseminated for improving patient safety; and adequate resources to maintain the system. Innovative program features may be of interest to other States implementing reporting systems.