Three concepts associated with ‘good governance’, referring to the quality of governance processes and outcomes, are examined in this chapter: accountability, legitimacy and trust. For each concept, definitions are reviewed and characteristics identified. The chapter investigates accountability through key themes of complexity and challenges associated with delivering on downward accountability in the context of decentralisation. Complexity arises from the number and range of actors involved in co-management, situated at different administrative levels, with multiple demands on and mechanisms for accountability. Different forms of legitimacy and trust are introduced and reviewed, including input, output and throughput legitimacy and dispositional, rational, affinitive and procedural forms of trust. Challenges to delivering and maintaining legitimacy and trust in the context of co-management and solutions to these are identified.