This thesis describes history of Catalan nationalism and analyzes the motives that lead to separatist tendencies in Catalonia. It also focuses on the impact of devolution and separation on Catalonia and Spain. Catalans are a historic nation with their own language and traditions. Since the establishment of the Kingdom of Spain they have sought a greater autonomy within pluralistic Spain until now. In the history, they experienced numerous efforts of assimilation and suppression, mostly during the dictatorship of General Franco. But the Catalans defended their uniqueness and during the transition to democracy and with the new Constitution of 1978, they gained considerable portion of autonomy. In the history, Catalans did not demand independence, they wanted to be part of the federal Spain. However, due to the economic crisis and the rejection of the greater autonomy, Catalan nationalism converted to separatism.