In an increasingly globalised world, cities and regions sometimes join forces with their neighbours to form "megaregions" and tap economies of scale. This report discusses how eight cities and counties in Norway and Sweden - along the coast joining up Oslo, Gothenburg and Malmö - have decided to work closer together as the megaregion of “Western Scandinavia”. With a total population of about 5 million inhabitants, this cross-border territory shows good potential to draw on its growing economic and cultural interlinkages, as well as its long history of institutional collaboration, to build a stronger, more sustainable and more inclusive megaregion. The report encourages local authorities to identify a common vision for their shared future development and to take concrete action towards implementing it. It also calls for national governments to tackle the challenges of cross-border transport planning to facilitate greener mobility and more inclusive labour markets.