Can platforms close the governance gap in the sharing economy, and if so, how? Through an in-depth qualitative case study, we analyze the process by which new regulation and self-regulation emerge in one sector of the sharing economy, crowdfunding, through the actions of a meta-organization. We focus on the principal French sectoral meta-organization, Financement Participatif France (FPF-Crowdfunding France). We show that this multi-stakeholder meta-organization not only closed the governance gap through collective legal, ethical, and utilitarian work but also preceded and shaped the new market. We present a hybrid governance approach combining a) soft multi-agency regulation, b) self-regulation through a process of "partial meta-organizing", and c) direct civil society participation. We expand the literature by highlighting features of partial meta-organizing by sharing economy platforms and by identifying conditions for successful joint regulation and self-regulation of the sector.