The concept of "knowledge brokerage" focuses on promoting the integration of the best available evidence into policy and practice-related decisions. In this study, emphasis is put on the knowledge brokerage role of cities. The study aims at finding similarities and differences in existing educational knowledge brokerage initiatives, at exploring the effectiveness of knowledge brokerage initiatives, and at explaining differences in the effectiveness of educational knowledge brokerage initiatives. Four medium-sized cities were investigated using a case study methodology. During the case studies a qualitative approach using document analysis and in-depth interviews was adopted. The article firstly describes the existing knowledge brokerage initiatives. The descriptive part also looks at the effectiveness of the studied knowledge brokerage initiatives by describing their (un)intended results. Afterwards three clusters of factors are introduced that can explain differences in the success of brokerage initiatives of cities: the policy context, the users and their organisation, and the knowledge brokerage system. The article stresses the importance of a context of trust, and a context that stimulates data use, and elaborates on findings regarding the impact of data literacy, data culture, the organisations' policy-making capacities, and a sense of urgency. (Contains 3 figures.)