Within this article, the strengths and weaknesses of crowdsourcing for idea generation and idea selection in the context of smart city innovation are investigated. First, smart cities are defined next to similar but different concepts such as digital cities, intelligent cities or ubiquitous cities. It is argued that the smart city-concept is in fact a more user-centered evolution of the other c/fy-concepts which seem to be more technological deterministic in nature. The principles of crowdsourcing are explained and the different manifestations are demonstrated. By means of a case study, the generation of ideas for innovative uses of ICT for city innovation by citizens through an online platform is studied, as well as the selection process. For this selection, a crowdsourcing solution is compared to a selection made by external experts. The comparison of both indicates that using the crowd as gatekeeper and selector of innovative ideas yields a long list with high user benefits. However, the generation of ideas in itself appeared not to deliver extremely innovative ideas. Crowdsourcing thus appears to be a useful and effective tool in the context of smart city innovation, but should be thoughtfully used and combined with other user involvement approaches and within broader frameworks such as Living Labs.