The Passenger Environment Survey (PES) conducted by New York City Transit (NYCT) of the Metropolitan Transit Authority uses a quantitative and scientific approach to measure the perceptions of NYCT’s 7.3 million daily riders. With 6,485 subway cars, 4,576 buses, and 468 stations in a 321-mi² service area and a population of more than 8 million, quality assurance is a colossal undertaking. PES takes a passenger-centric approach by measuring indicators from the customer’s perspective. Since its inception in 1983, PES has evolved to include 68 indicators in four distinct categories measured in four passenger environments: subway cars, subway stations, local buses, and express buses. The consistent and well-defined PES standards are clearly understood by operations personnel. Approximately 25 dedicated surveyors, who do not report to operations management, produce semiannual reports with statistical precision exceeding 95% ± 5%. The data are subject to validation and rigorous quality control by trained statistical analysts. Central to the PES program is NYCT’s genuine willingness to understand the customers’ experiences and to represent customers in quality assessment. Internally, PES functions as a performance audit. Monthly reports bring the attention of operations management to deficiencies that have been observed. The results are considered in promotion and merit decision-making processes. Externally, PES serves as a dispassionate and analytical measure of the passengers’ experiences. Reported semiannually, the scorecard demonstrates long-term progress in continuous improvement. NYCT regularly receives requests from agencies nationally and internationally wishing to model their quality control programs after the program conducted through the use of PES. This approach demonstrates the dedication of NYCT staff in maintaining a friendly and comfortable system, in good repair, of which every New Yorker can be proud.