This book offers a substantial and up-dated discussion and presentation of the new European “frontiers” related to complex and controversial social and spatial (re)integration issues in multicultural and border regions. It represents an inter-disciplinary endeavour from human geographers, social and political scientists, and linguists to understand and interpret the current developments of the European “unity in diversity” paradigm, based on simultaneous and continuous processes of social and spatial convergence and divergence, changing territorialities and identities, particularly in the wider EU’s “inner” and “outer” border regions. These studies convincingly display the prominence of context in understanding the regional and local geo-histories and in making sense of the meanings of borders for social communities and wider societies. They also show how (re)integration potentials of border and multicultural regions are strongly dependent on the creation of a viable multi-level social and spatial planning and cooperation system, within which both “conflict-to-harmony” processes and “common cause” behaviours and practices may become effective, and thus give a new role to local communities in the numerous borderlands across Europe. The book offers both a synthesis of current theoretical-methodological approaches and an analysis of selected case-studies provided by internationally-acknowledged scholars. It represents a valuable instrument for researchers and students of social and spatial integration, human and political geographers, social anthropologists, and social and political scientists, as well as language planners.