Presently, institutional systems and practices in marine/maritime spatial planning (MSP) are evolving rapidly. At the same time, cross-border learning and exchange are still at an early stage. This chapter is based on the need to assess and compare participation processes across cases and countries and foster learning to develop public participation in MSP. Based on theoretical reflections, but anchored in results derived from the BaltSpace and the Baltic SCOPE projects, we present an analytical framework to characterise participation in MSP, including a participation ladder emphasising power sharing, roles, functions and learning. It is inspired by the land-based planning discourse, rural development literature, natural resource and conflict management and the latest publications with an MSP perspective including one in this book.