Marine protected areas (MPAs) are increasingly being developed and utilised as management tools in efforts to protect and manage marine biodiversity and fishery resources in Northern European seas. In May 2004, a Workshop on the Development and Management of Marine Protected Areas was held in Kasnäs, Finland. The aim of the workshop was, through presentations, discussions, tutorials and group sessions, to equip the participants with the most important practical and theoretical tools, methods and approaches needed in selecting, developing and managing MPAs. This report is a documentary of the workshop, and it includes summaries of presentations, main outputs from group sessions and other useful information.