The excessive use of cars is responsible for individual, environmental, economic and social problems. As a consequence, the development of measures to reduce car use and encourage the use of sustainable modes of transport is needed. One strategy considered efficient is the change to public transport, as this transportation mode offers several advantages, especially when operated with quality. The use of public transportation, however, is influenced by environmental, socio-demographic and psychosocial variables. In this investigation, we test an integrated model to verify how the following psychosocial variables influence the use of public transport: intention, perceived behavioral control, attitude, personal norm, social norm, guilt, problem awareness and awareness of consequences. We performed a comparative study between two samples: one in the Federal District-Brazil (n = 312) and another in the region of Hampton Roads-VA-United States (n = 518). Participants responded to an online survey consisting of 31 item scale and socio demographic questions. The instrument was submitted to semantic validation procedures, confirmatory factor analysis and measurement invariance tests, to ensure its reliability and suitability to measure the same constructs in both samples surveyed. The invariance of the causal relationship between the variables arranged in the model was also tested, to identify whether the estimated models were equivalent for both samples. Finally, we compared the causal relationships found in both models. The results indicated equivalence between the two samples, regarding both the measures and the causal relations between the variables of the model. The estimates of the model fit indices were satisfactory in both samples. Comparing the models, more similarities than differences were found, which may be attributed to both the universality of the tested theoretical model, as well as the contextual similarities between the two regions investigated. The intention was a strong predictor of behavior, being mainly influenced by the perception of behavioral control. This result reveals that the more people realize that using public transportation is an easy behavior to be undetaken, the greater their intention to use this mode of transport. Normative and control beliefs were more relevant in predicting the intention then pro-environmental orientation. Differences were found regarding the role of attitude and personal norms for expressing intentions as well as the influence of attitude and feelings of guilt for the perception of behavioral control. We suggest interventions for bring about an increase perceived control, so that public transportation can be seen as an easy transportation option. It is estimated that perceived control, intention and public transportation use could be increased by providing information, encouraging the use, and improving the service quality.
