In the current European dilemma as to whether to increase diversity policies or move towards an assimilationist policy, it is difficult to know what the Spanish approach is. This book argues that Spain represents a context of "multiple diversity", where two frameworks interact: an old, unresolved one, arising from democratic transition, and a new one due to immigration. This explains the Spanish practical approach, where the recent past plays the role of an iron cage, limiting institutional innovation and change. The author proposes a heuristic model, to better understand the "Spanish laboratory of diversities". In order to go through these steps, the author analyses three case studies, coming from the political/social agenda: education, workplace, and political rights. At the end, the reader will have an empirically informed and theoretically founded overview on how Spain is managing diversity. This book is timely for a wide range of academic and professional readers.