This chapter explores a particular dimension of that growing interest, namely the governance of transformative social innovations (TSIs) and focuses specifically on the challenges that emerge during institutionalization processes. It situates understanding of the capture dynamics in TSI institutionalization processes in the wider literature on transition governance. The chapter argues that the activities can be fruitfully analyzed by concentrating on the forces at work during specific periods of transformation and capture with respect to dominant institutions. Their work shows the extent to which transition-oriented analyses of institutionalization might be unworkable. The chapter draws on empirical material collected from two extensive case studies that we conducted as part of a larger project on TSI in Europe and Latin America. After a description of their organizational features and aims as transnational networks of transformative social innovation. The chapter discusses their impacts and the processes of capture that they have confronted during attempts to institutionalize their ambitions.