To understand fully passengers' perceptions and expectations of the bus service quality in Taipei, business managers and governmental agencies must seek a proper scale that can reflect passengers' opinions accurately. This study develops and tests a service quality scale designed for a city bus transit system in Taipei. Churchill's paradigm and a focus group interview were combined into a multistage scale development procedure. Based on the procedure, Taipei city buses were selected as the example, for which a service quality scale was developed. The final scale contains four dimensions and 20 items. These four dimensions are 'interaction with passengers', 'tangible service equipment', 'convenience of service' and 'operating management support'. Finally, the results of scale development and the managerial applications of the service quality scale for the city transit system are discussed.