© 2020 Elsevier Ltd Introduction: In recent years, there has been growing interest in studies integrating social cognitive and environmental variables as predictors of active transport to school (ATS). However, a theoretical model of associations between children's ATS and these variables has not been well established. The aims of this study were (1) to develop and test a model which conceptualized relationships between children's ATS and psychological, social cognitive and perceived environments; and (2) to assess direct effects among these variables. Methods: Data were drawn from the ProATs, a cross-sectional study conducted with 1189 children aged 9–12 years from 11 primary schools in Huesca, Spain between January and June 2018. A child self-reported questionnaire was used to measure sociodemographic characteristics (age, sex), school travel mode (ATS: walking, cycling; non-ATS: by car, by motorcycle, by bus), and social cognitive and perceived environments. The social cognitive environment was measured based on four constructs of the theory of planned behavior (intention, attitude, social norm, perceived behavioural control), and three constructs of the basic psychological needs (autonomy, competence, relatedness) in the self-determination theory. The perceived environment was assessed through the security and accessibility of neighborhood environmental barriers to ATS. A structural equation modelling technique was utilised to examine direct effects of social cognitive and perceived environments on ATS. Results: The model achieved acceptable fit, explaining 48% of the variance of children's ATS. Perceived behavioural control was the strongest predictor of intention, and influenced by autonomy, competence and the perceived environment. Conclusions: Social cognitive and perceived environments played important roles in predicting children's ATS. Future interventions might consider strategies to increase perceptions of autonomy, competence and behavioural control along with strategies aimed to foster more positive perceptions of the built environment.