This chapter focuses on nongovernmental organizations (NGOs) in policy analysis in institutional spaces in Colombia. It explains how NGOs exert substantial influence on social, political, and economic spheres globally, representing diverse efforts of collective action, political intervention, social service delivery, and watchdog activity over government and business sectors. It also elaborates that NGOs provide many public services and advance many other important public goods through policy analysis and advocacy. The chapter reviews definitions and terms related to the third sector in the context of Colombia, followed by an outline of Colombia's third sector government relations over the past several decades. It also examines the role of NGOs in policy analysis through the lens of the Colombian Confederation of Nongovernmental Organizations in the postagreement, the peace process, and in the implementation and monitoring of the Sustainable Development Goals in Colombia.