In the UK, Right to Challenge is a way to give citizens the opportunity to challenge a public task. Rotterdam is one of the Dutch cities who applied this approach. The Right to Challenge Rotterdam is being evaluated at this moment and the Erasmus University participates in this evaluation. We participate in the process evaluation of the municipality and we enrich the results by scientific knowledge on bottom-up initiatives and by comparing Rotterdam with other Dutch cities. During the evaluation, the preliminary results are used to adapt the arrangement Right to Challenge Rotterdam.