Joint management of protected areas is promoted in many countries around the world. It is considered a means to provide local communities, including indigenous people, with recognition of their cultural practices in the use and management of the natural resources within a protected area, while working together with governments to achieve conservation goals. However, implementation of effective joint management has often been difficult because capacities and expectations among partners differ. Here we explore the potential of using a participatory monitoring and evaluation approach as a means of not only agreeing among partners on the objectives of joint management but also of measuring progress toward those objectives. In particular, we first describe the process used to develop criteria and indicators for measuring joint management effectiveness of a protected area in the Northern Territory, Australia, involving the park's Aboriginal Traditional Owners, their legal representatives, government, and researchers. We then analyze the process of applying a participatory approach to developing indicators and its contribution to improving equity among the partners. We consider the effectiveness of a participatory process within the context of the relationships, capacities, skills, communication, and cross-cultural information sharing. We found that at the early stages of joint management, the partners mostly identify process indicators related to human and social capital assets. Cross-cultural engagement in the early stages of the monitoring and evaluation cycle is challenged by issues relating to communication, institutional and community capacities, representation, and flexibility in ways of working together while learning by doing. We conclude, however, that a participatory monitoring and evaluation approach in which partners agree equally on the identification of criteria and indicators to measure agreed management outcomes has the potential of improving equitable participation, decision making and working relationships, which in turn will lead to improved park management effectiveness and community outcomes.