In this paper it is studied the formation of left and right political spaces in Spain during the twentieth century, especially on two stages: the ’30s, since the proclamation of the Second Republic in 1931 until the end of Civil War in 1939 (the terms left and right are then normally incorporated in the partisan denominations); and the democratic transition of current Spain from 1975 to 2012. Both cases emphasize the difficulty to develop a centre political space and a certain polarization. In the first case this situation led to war. In the second case has articulated a permanent opposition which, although it has changed in nature, it is still ruled by the right-left axis.
Keywords: Republic, Popular Front, Left, Right, Civil War, Democratic transition