Lately, the concept of smart cities has been changing from a top-down and mostly technological-driven approach, towards a bottom-up process that facilitates participation and collaboration among city stakeholders. In this latter respect, the city is an ecosystem in which smart applications, open government data, and new modes of participation are fostering in- novation. However, detailed analyses on how to manage bottom-up smart city initiatives, as well as descriptions of underlying challenges and barriers, are still scarce. Therefore, this article investigates four collaborative smart city initiatives in Europe to learn how cities can op- timize citizen involvement in the context of public sector innovation. The analytical framework focuses on the different stakeholder roles in the ecosystem and the civic capacities to participate in the innovation process. The findings illustrate how more inclusive citizen involvement can be realized by providing different tools that align with the specific capacities and skills of the citizens. Furthermore, through specified workshop formats and peer learning, citizens lacking technical skills were also enabled to participate in the evolution of their cities, and to generate solutions from which both the city and everyday urban life can possibly benefit.