From the 1980s onward movement scholars have increasingly emphasized the significance of collective identity as a factor stimulating protest participation. Sociologists were among the first to emphasize the importance of collective identity in protest participation. They argued that the generation of a collective identity is crucial for a movement to emerge. Similarly, social psychological studies report consistently that the more people identify with a group the more they are inclined to protest on behalf of that group. Apparently, identification with a group is an important reason why people participate in protest on behalf of that group. In order to understand why, we must elaborate the identity concept.