Framed by social exchange theory and Weber’s theory of substantive and formal rationality, this study investigates the mediating role of residents’ perceptions of tourism impacts. It examines whether community attachment, environmental and cultural attitudes, economic gain, and community involvement directly impact upon residents’ support for tourism development, or if their influences are mediated by perceptions of tourism impacts. Data were collected from residents within two historical cities in Iran: Kashan and Tabriz. The findings reveal that residents’ perceptions of tourism impacts play a significant mediating role in shaping the relationships between community attachment, environmental attitudes, and economic gain on support for tourism development. However, the results do not support the indirect effects of cultural attitudes and involvement on support for tourism development. This study thus extends extant knowledge by highlighting the mediating role played by residents’ perceptions of tourism impacts, comparing direct and indirect effects on support for tourism development.