Purpose - The purpose of this paper is to introduce the special issue on improving equitable access to health care through increased public and patient involvement (PPI) in prioritization decisions by discussing the conceptualization, scope and rationales of PPI in priority setting that inform the special issue. Design/methodology/approach - The paper employs a mixed-methods approach in that it provides a literature review and a conceptual discussion of the common themes emerging in the field of PPI and health priority setting. Findings - The special issue focuses on public participation that is collective in character, in the sense that the participation relates to a social, not personal, decision and is relevant to whole groups of people and not single individuals. It is aimed at influencing a decision on public policy or legal rules. The rationales for public participation can be found in democratic theory, especially as they relate to the social and political values of legitimacy and representation. Originality/value - The paper builds on previous definitions of public participation by underlining its collective character. In doing so, it develops the work by Parry, Moyser and Day by arguing that, in light of the empirical evidence presented in this issue, public participatory activities such as protests and demonstrations should no longer be labelled unconventional, but should instead be labelled as "contestatory participation". This is to better reflect a situation in which these modes of participation have become more conventional in many parts of the world.