Participatory research (PR) is on the rise. In Spain, PR is scarce in the field of health, although there is an increasing interest in the matter. A comprehensive understanding of the meanings and practical implications of "public participation" is essential to promote participation in health research. The aim of the study is to explore the discursive positions on PR among individuals with experience in participatory processes in different areas and how this understanding translates into practice. We conducted a critical discourse analysis of 21 individuals with experience in PR and participatory processes (13 women, 8 men), mainly from the field of health and other areas of knowledge. Sixteen were Spanish and the rest were from the United Kingdom (3), United States (1), and Canada (1). Interviews were conducted in person or by telephone. The fieldwork was conducted between March 2019 and November 2019. The dominant discourses on public participation are situated along two axes situated on a continuum: the purpose of public participation and how power should be distributed in public participation processes. The first is instrumental public participation, which sees participatory research as a tool to improve research results and focuses on institutional interests and power-decision making is hold by researchers and institutions. The second, is transformative public participation, with a focus on social change and an equitable sharing of decision-making power between the public and researchers. All discursive positions stated that they do not carry out specific strategies to include the most socially disadvantaged individuals or groups. A shift in the scientific approach about knowledge, along with time and resources, are required to move towards a more balanced power distribution in the processes involving the public.