Declining ridership, shrinking market share, and increasing operating costs have led many transit systems to adopt quality management strategies. These strategies help transit systems improve and evolve continuously by focusing on the customer (passengers) first. An integral step in adopting quality systems is measuring customer satisfaction. Using questionnaire data from the Athens, Greece, bus and trolley bus systems, this article demonstrates the potential use of structural equation modeling (SEM) for measuring customer satisfaction, and relays useful results regarding perceived service quality. The questionnaire results yield essential information in determining current and near-term requirements and customer expectations, helping set priorities for service improvements, identifying system weaknesses, targeting user groups and identifying their specific needs, and setting performance benchmarks that can be used to compare the system to its competitors and track its performance over time.