This special issue approaches regional planning as a contested arena of strategic planning. With this view, we transcend the idea that regional planning is purely a matter of scale and approach the complexity of regional planning from three perspectives: interests, institutions and relations. The perspective of 'interests' reveals the various underlying motivations connected to regional planning. The perspective of 'institutions' addresses the encounter of formal and informal rules, norms and discourses shaping planning and governance practices. The perspective of 'relations' uncovers the complex constellations of actors and processes associated with planning, involving various administrative scales, territorial entities and sectoral policies.