Mainstreaming is a feasible and viable option for scaling up initiatives on community-based adaptation (CBA) to climate change. However, there is little evidence on how to get CBA mainstreaming feasible and to work effectively. This paper aims to investigate two major questions: (1) what kind of policies favour mainstreaming CBA; and (2) what kinds of approaches or practices are required to operationalize CBA mainstreaming in the case of Nepal? The field research for this paper was conducted in the Dhading, Nawalparasi and Pyuthan districts of Nepal. The research used a mix of approaches and methods for data generation and analysis. The findings reveal that policies to operationalize CBA mainstreaming should build on past policy successes and include community-centric provisions that empower local institutions and encourage them to practice inclusive decision-making and benefit-sharing mechanisms. One lesson from this analysis of the practices of mainstreaming in Nepal is that an integrated co-management approach to mainstreaming is necessary to overcome the barriers related to knowledge, finance and technology. It is concluded that the operational mechanisms of mainstreaming CBA in development should have an inclusive local structure and be responsive to national policies and governance arrangements.