This chapter builds on insights from institutional theory to advance our understanding of the scaling up of social innovations. The authors define scaling up as a process that involves the institutionalization of social innovations, that is, their transmission from time-to-time and place-to-place. The chapter considers the influence on scaling of justification and cooptation; two forces identified in institutional scholarship to explain failure, as well as variation, in the replication and diffusion of new social structures. The chapter offers a framework to articulate the influence of these two forces via the institutional carriers – symbolic systems, relational systems, practices, and artifacts – involved in the transmission of innovations. It illustrates the value of the framework to understand the institutionalization of a contested inclusive social innovation: La Salada, a “paraformal” market located in Buenos Aires, Argentina. La Salada offers an unusual entrepreneurship staircase for the poor to create, develop, and grow their businesses from backroom workshops to legal or paralegal establishments.