The outbreak of the 15M or indignado movement in Spain in 2011 was the biggest episode of social unrest since the end of the Transition in the 1970s. Its emergence caught the political parties, media, trade unions and the most important community-based organisations and pre-existing social movements off guard. It targeted those who were identified as responsible for the recession and how it was handled - politicians and bankers -, and represented a global criticism of the existing political system and institutional framework. The 15M was not a youth movement, but a general movement criticising the current economic model, though it did have a large youth component in its initial stages. It was plural and diverse, and a wide broad spectrum of criticism and degrees of radicality and political awareness coexisted in the squares and camps. In general terms, the links between the indignados and the labour movement were weak and marked by mutual mistrust. The 15M movement was a milestone in the political trajectory of Spain and opened up a regime crisis that would deepen thereafter.