This report overviews lessons learned during the Baltic Urban Lab project, One of Nordregio’s tasks in Baltic Urban Lab has been to observe and analyse the methods for stakeholder involvement and participation that the cities tested during the project period. The main approach has been to observe what can be done to involve private actors, local inhabitants and other public departments in the planning process, as well as to understand what can be gained by applying a 4P-approach to the planning of brownfield areas around the Baltic Sea.