The New York State Energy Research and Development Authority (NYSERDA), under its Alternative Fuels for Vehicles Fleet Demonstration Program (AFV-FDP), monitored the operation of 31 compressed natural gas (CNG) transit buses divided among five transit properties in New York State. The CNG buses were delivered in 1992 and have accumulated over 3.73 million kilometers (2.32 million miles) of operation through September 1995. Data collected included fuel consumption, maintenance histories, acceleration, driveability, and emissions. Several of these buses experienced problems with defective pressure relief valves though no accidents resulted from these failures. During the period of operation, various upgrades and learning experiences have contributed to improved operations and lower emissions, though variations in emissions were observed due to drift in fuel system calibration. This paper summarizes the findings of the operation of the CNG transit buses and compares these results to recent CNG transit bus engine and fuel system developments.