The chapter looks at how learning occurs in ASEAN, given its state-centric institutional design, which offers limited engagement with non-state actors. It addresses the question of how the participation of transnational networks in ASEAN’s climate governance efforts enables collective learning. Applying the communities of practice theory, it argues that knowledge is embedded in the practices of actors involved in ASEAN processes. Hence, their practices can constitute climate change governance through collective learning, which is both a process and an outcome. As a process, participation in governance allows members to learn from each other as they engage in joint activities. As an outcome, it is assumed that collective learning can be reflected in policies and programs. To illustrate how participation enables collective learning, the chapter examines the shared practices that led to the creation of the 2018 ASEAN Guidelines for Agroforestry Development using semi-structured interviews and documentary analysis. It focuses on the interactions of state and non-state actors operating in transnational governance climate networks and their shared practices in terms of boundary encounters, brokerage activities, and epistemic boundary objects. By doing so, the chapter demonstrates that collective learning in communities of practice can serve as a building block of regional climate governance.