This study deals with the concept of Responsible Research and Innovation (RRI), with a focus on Public Engagement as one of its main dimensions and the roles identified within. By undertaking a broad review of the related literature as well as an empirical study, this work investigates problems of practical implementation. It describes origins and developments of Public Engagement in research and innovation and closes with options for future direction. The work presents the central role of practitioners identified within the discourse and encompasses suggestions and recommendations for Public Engagement processes as revealed by the empirical work with practitioners in the field. Finally, it describes consequences that could be obtained from the results presented. It raises issues and open questions on Public Engagement in Responsible Research and Innovation which would need extra attention.