Efforts are intensifying to spur innovation in the public sector, and multiactor collaboration seems to offer a viable strategy for doing so. However, though government actors are relatively keen to involve citizens and civil society actors in the design and implementation of innovative solutions, co-initiation of public innovation is rare. As a result, local governments often fail to tap into the experiences, ideas, and resources of civic actors when identifying and defining problems and challenges that call for innovative solutions. To explore the conditions, process, and impact of co-initiated public innovations in urban spaces, this article analyzes three Danish cases of co-initiation. The empirical cases are described and compared to identify the conditions of co-initiation, describe the different phases in the collaborative process, and assess the various impacts. The article also reflects on the role of institutional design and leadership in facilitating co-initiation of collaborative innovation.