The Baltic macroregion is a platform for the development of different areas of international cooperation, which are an important factor affecting the socioeconomic growth of the region states. The deteriorating political relations between Russia and its Baltic neighbours complicate the development of mutual connections. However, economic and sociocultural cooperation and joint environmental projects continue despite all the difficulties. Based on recent studies carried out by Russian and Polish researchers, this book examines current trends in the socioeconomic development of the region countries and various forms of transboundary cooperation and provides recommendations for further development. Special attention is paid to sustainable environmental management and environmental protection, transboundary ties among companies and among people, the development of international tourism, opportunities for reinforcing the contact function of the border, and spatial planning. The book addresses theoretical problems that are of crucial significance to economic development and transboundary cooperation, namely, those of path dependence, the emerge.