A new regime of science production is emerging from the involvement of non-scientists. The present study aims to improve understanding of this phenomenon with an analysis of 16 interviews with Spanish coordinators of participatory science practices. The results indicate a majority of strategic and captive publics and point to communication as a key tool for the development of successful practices. Five key elements of the degree of integration required to develop a citizen participation in science practice were analysed: derived outputs, level of participant contribution, participation assessment, practice replicability, and participant and facilitator training. Proposals for strategies to remove barriers to citizen participation are the study's principal contribution.