Co-management is in essence about collaboration and participation. In this chapter, definitions are provided for each, with recurring themes identified from definitions of collaboration and collaborative governance. The chapter explores these key themes in relation to the ‘what, who, how and why’ of collaboration, moving to distinguish between cooperation, coordination and collaboration, the nature of leadership in collaboration and the relevance of scale. The chapter then moves on to review the meaning and practice of participation, reflecting on the ‘why, who, how and when’ of participation. Challenges to meaningful participation are identified, noting critique of the adoption of a mechanical, technical approach rather than recognising the political and empowering potential of participation.