While direct forms of democracy are heralded as the panacea to declining trends in voting behaviour and the increasing rejection of the way formal politics is conducted, little is known about the willingness of citizens to perform this role. This study aims to provide quantitative estimates of the proportions of citizens who would be willing to be involved, and to what extent, in health service policy and planning in primary care, a hospital board and the Catalan Health Department. Findings show which participatory mechanisms have been used and are believed to be the most useful, at the individual and collective levels, through comparing members of civil society groups (n=160) and unafflilated citizens (n=696), and explain the relationship between the desire for involvement and the pre-disposing factors of personal capacity, organisational opportunity, personal and organisational mobilising factors and motivations based on individual and collective incentives.