Democratic forest decentralization is often justified by expectations of greater management effectiveness and increased equity of access to forest benefits; yet these outcomes do not always coincide. It is proposed that to enhance understanding of the outcomes of theoretically progressive decentralized forest policies in varying and dynamic contexts, the processes through which the legitimacy of local forest regimes is constructed and contested needs to be better understood. This case study of northeastern Tanzania finds that the current outcomes of Community-Based Forest Management, favouring conservation over exploitation, precariously depend on contested claims to legitimacy embedded in intra-community social and political dynamics. To broaden the bases of legitimacy of community forest governance, and to enhance its long-term sustainability, structures for improved deliberation, representation, and accountability should be supported.