This book deals with the structure of Spanish politics: how citizens and parties locate themselves in political space, and how these actors make decisions based on their positions in the various dimensions this space consists of. The authors of this volume address the questions surrounding the dimensions of Spanish politics, the effect of the nationalist issue (Catalonia and the Basque Country) in Spanish political competition, the reasons for which the Catalans and the Basques appear as more left-wing than the rest of Spain, the ways in which Spanish voters make their choices, the political issues that are more polarizing in Spain, the background behind why the two main parties hold such similar positions on redistribution, whether the territorial conflict has an impact on preferences for redistribution and how the immigration issue alters political competition. All of these questions rely on the spatial theory of politics for their analyses. The data used in all the chapters come from a survey that was especially designed with the aim of addressing all these topics that are examined in the book. This is the first exhaustive and rigorous explanation of how Spanish politics work based on the positions that parties and citizens occupy in the political space. This book was published as a special issue of *South European Society and Politics*.