In this study we examined the role of trust as a mediator in social exchange between teachers and their school, particularly between perceived procedural justice and perceived organizational support, on the one hand, and teachers' affective organizational commitment and organizational citizenship behaviour, on the other hand. A model was developed that distinguished between trust in three agents: team members, the supervisor and higher management. The model was tested in the context of Dutch schools for vocational education and training on a sample of 845 teachers. Data was collected using questionnaires and was analysed with structural equation modelling. Results show that trust was a predictor for desirable teacher outcomes and a mediator in social exchange. In particular trust in team members was related to affective organizational commitment and organizational citizenship behaviour. Trust in the supervisor and trust in higher management were neither related to organizational commitment nor to organizational citizenship behaviour. Perceived organizational support was related to teachers' trust in all trust targets. It also had a direct effect on organizational commitment. Procedural justice influenced trust in the supervisor and trust in higher management. The authors discuss the results in light of previous findings and the context of the study.