This book offers a novel interdisciplinary approach to interpret the emergence of the Basque-Spanish nationalist conflict. It incorporates into sociological analysis the understanding of law put forward by legal realism and legal pluralism to answer some of the most pressing problems encountered in historical research on this topic. It does so by carrying out a comparative historical analysis which focuses on the puzzle produced by the political trajectories of two traditionally considered Basque territories between 1841 and 1936: Navarre and Vascongadas - the precursor of today's Euskadi. Urasstabaso Ruiz argues that the historical and ideological trajectories of these territories need to be understood in relation to