This study develops a model of residents’ support for conservation using social exchange theory, complemented by the concept of participation in decision making borrowed from the Arnstein’s Model of Participation. The framework posited that residents’ support for conservation is influenced by the trust in conservation authorities and perceived benefits, and trust is determined by perceived benefits. It uniquely posited that participation in decision making indirectly influence support for conservation through its effects on trust and perceived benefits. The model was tested using a questionnaire survey to 543 local residents in Zanzibar Stone Town in Tanzania. Results from structural equation modelling indicate that residents’ support for conservation is significantly influenced by the trust in conservation authorities and perceived benefits. Results also show that support for conservation is indirectly influenced by residents’ participation in decision making, which inherently influences residents’ trust in conservation authorities and perceived benefits. The contribution of the study to the body of knowledge emanates from the addition of the participation in decision making variable in the social exchange model and the testing of the model in a relatively neglected setting of cultural heritage. The study discusses the practical implications and provides some suggestions for future research.