This article examines a case of participatory social policy in which former beneficiaries were invited as ‘experts-by-experience’ into Finnish social welfare organisations. It combines a governmentality perspective with the analytical tools of the sociology of engagements to explore as what the projects’ participants are engaged, and how the differing demands made on their ways of being are made to appear as legitimate. The article shows how different definitions of expertise are used to steer the participants’ forms of engagement, and how these definitions appear valid only within a specific frame of justifying civic participation. It concludes that the participants’ expertise is defined in terms of their ability to ‘projectify themselves’ according to the projects’ specific objectives: rehabilitation, co-production, or the exercise of civic rights. The article suggests that this demand to align one’s way of being with project purposes is what makes it possible to evaluate and select participants.