A sample of 200 complaints filed to a public transport company and 210 negative critical incidents (NCIs) obtained from on-board interviews were analyzed with the purpose of inferring perceived service quality (PSQ) attributes of public transport. The most frequent complaints and NCIs concerned employee behavior and punctuality, followed by missing or inaccurate information and inadequate planning. In a follow-up mail survey, a representative sample of 997 respondents reported if they remembered having experienced prototypical NCIs constructed on the basis of the complaints. Confirming the validity of the inferred PSQ attributes, all NCIs were reported to have been experienced by at least some respondents. NCIs related to employee behavior were, however less frequently remembered, whereas those related to vehicle design and space, punctuality, and traffic planning were more frequently remembered. Taken together, the results suggest that PSQ attributes in public transport refer to employee behavior, reliability, and simplicity. Finally, inferences made from customer complaints and negative critical incidents are shown to extend our knowledge of perceived service quality attributes in public transport.