Left critiques of professionalized liberal social change actors such as human rights groups, development organizations, and philanthropic foundations accuse them of depoliticizing or coopting radical social movements. But what happens when the professionals in these third sector institutions take up these critiques and reimagine human rights, development, and philanthropy in their light while maintaining and rearticulating their liberal commitments? This dissertation locates and investigates a search for a more ambitious and political kind of liberal social change by elite progressive civil society professionals in the first two decades of the 21st century. By examining the discourses, tools, and practices these professionals construct to support social movements, it considers the epistemological assumptions, elite self-fashioning, and metaphorical structures that underwrite the entrance of movements into liberal social change projects. The dissertation finds that the terms for progressive third sector elite to support social movements involve assimilating them to ‘civil society’, which they imagine as an ‘ecosystem’ made up of different kinds of organizations and actors, each with a role to play. The function of movements, as the actor assumed to be most insulated from and oppositional to the encroachment of market and state power on civil society, is to provide cohesion, direction, and legitimacy to the other, more professionalized and compromised, actors. To avoid coopting movements, these professionals argue that grassroots activists possess privileged knowledge of social problems, while simultaneously fashioning themselves as neutral instruments used by movements to realize their solutions. The dissertation thus analyzes tools including participatory grantmaking and the social change ecosystem framework that third sector professionals develop to secure a non-coopting solidarity relationship with movement actors. These tools are ultimately designed to ensure the autonomy of social movements from elite influence so that the movements can redeem a civil society sphere in crisis. In the process, however, these tools and discourses engender a distinction between elite and ‘authentic’ political actors, cede responsibility for securing social change to the latter, while framing the telos of that action as the redemption of a space (civil society) that exists alongside rather than as a fundamental challenge to the power of capital and state. The dissertation theorizes this set of discourses and practices as a key aspect of ‘movement liberalism’, and argues that it remains to be seen the extent to which actually existing movements are conscripted to its project, but that critiques of liberalism nonetheless need to account for both its enchantment with and aversion to ‘the political’.