For decades, user participation has brought value to various systems development projects. Today, there are expectations that public e-service development will experience the same benefits. However, existing research has shown that introducing user participation into public e-service development can be challenging. In this study, we interviewed citizens in order to explore their willingness and ability to participate in public e-service development according to three user participation schools: User-Centred Design, Participatory Design and User Innovation. Our findings show that citizens in general are willing to participate, but their ability to do so is limited. Based on our findings, we developed nine propositions to explain citizens' willingness and ability to participate in public e-service development. The propositions contribute to practice by acting as a tentative guide for systems developers when they use user participation schools as inspiration in public e-service projects. They also act as a starting point for future research into conditions for user participation in public e-service development. (C) 2014 Elsevier Inc. All rights reserved.