Policy research on science, technology and innovation (STI) significantly brings not only impact on government policies but also benefits to business and society. The UK, where rigorous STI policy research has been conducted, is selected as the case investigated in this study. This study first attempts to problematize what current STI policy research communities are by evaluating knowledge structure and collaboration structure of the UK STI policy research communities, and then expand on the roles STI policy research communities play in policy practice. Therefore, the relationship between STI policy research communities and policy practice is characterized by several elements that exist between STI policy research communities and government, i.e. institution, interface and interaction. Also, the knowledge created by STI policy research communities is analyzed in order to uncover fundamental bases of communities' contributions to policy practice.