Grassroots and community-based organizations mobilize ‘ordinary’ people in peacebuilding processes, initiating wide-ranging and contextually specific action which is crucial to the ‘bottom-up’ transformation of personal, relational, structural and cultural dynamics of conflict-affected societies. Contributions made by these organizations inform and drive activity in a range of sectors relevant to peacebuilding, including providing services for victims and survivors of conflict, reintegration of combatants, economic and political representation, transitional justice, memory work, commemoration and many more. Grassroots organizations reflect the contestation and socio-political divisions of the societies from which they emerge, which presents complex challenges but also ensures a diversity of perspectives and experiences are incorporated in the consolidation of peace. In the internationally orientated contemporary discourse of peacebuilding, the agency and potential of grassroots organizations tends to be homogenized and marginalized in favor of top-down, liberal peace interventions. This entry explores the forms and functions of grassroots organizations working to build peace and considers the contextual and structural constraints they face in light of hegemonic liberal peacebuilding discourses.