This Cambridge Element aims to advance theory by investigating the nature of participation in public service delivery. It situates itself under the theory of Public Service Logic to advocate for a strategic orientation to participation as an element of value creation in public services. It introduces the concept of participation and discusses the motives, incentives, and tools to engage citizens in public service delivery processes. Then, it frames citizens' participation under the approach public service ecosystem to capture the dynamic relationships among citizens, other actors, processes, and structures that may contribute to determining value in public service delivery. It presents the dynamics of value creation and destruction in public service. The Element concludes with implications for research and practice. This title is also available as Open Access on Cambridge Core.