Participation has emerged as a key theme for social policy and administration in the UK. Public service providers are often keen to consult users, and users themselves want to make their voices heard. Despite this, however, there is a perennial problem in getting people to participate, and participation is often better supported in principle than in practice. The motivations of key actors are crucial, but are often poorly understood. This article attempts to build a more detailed understanding of the motivations to participate of one key group: service users. Using Mutual Incentives Theory, it shows the extent to which users are motivated by individualistic or collectivistic concerns. These “demand side” factors are then combined with others on the “supply side” in a model we call the “participation chain”. This model provides a systematic framework for understanding what makes public service users participate, and seeks to demonstrate that, while the question of participation requires a combination of answers, it is a combination that can be predicted, planned for and acted upon.