There is a lack of research on the meta-organization creation process despite it being central to understanding this form of organization (Ahrne & Brunsson, 2005, 2008; Valente & Oliver, 2018). In this paper, we investigate the process that underlies the creation of Multi-Stakeholder Meta-Organizations (MSMOs). We explore MSMOs ‘in the making’ through a multiple case study of four meta-organizations with a social innovation purpose. We identify a three-stage MSMO creation process that takes place through the simultaneous occurrence of three major elements: the logic of action of MSMO members, MSMOs’ evolving boundaries, and their organizing practices. We show that the MSMO creation process is based on the coordination, negotiation, and actualization of the practices of meta-organization members rather than on structural conditions. In addition, the MSMO creation process begins with the involvement of a leading organization, which decides to create an informal group of member organizations before the effective creation of a formal organization.