Policy documents and academic literature suggest that Clean Development Mechanism (CDM) finance could complement traditional ‘energy access’ (EA) funding in developing countries, including the Least Developed Countries (LDCs). Yet these propositions have not been empirically tested. This study helps fill this gap by examining constraints to CDM project passage through five stages of an idealized project development cycle (PDC) in Tanzania, and their implications for the ability of the CDM to contribute to financing energy access in LDCs.