The anti-austerity movement in Spain, also referred to as the 15-M Movement (Spanish: Movimiento 15-M), and the Indignados Movement, was a series of protests, demonstrations, and occupations against austerity policies in Spain that began around the local and regional elections of 2011 and 2012. Beginning on 15 May 2011, many of the subsequent demonstrations spread through various social networks such as Real Democracy NOW (Spanish: Democracia Real YA) and Youth Without a Future (Spanish: Juventud Sin Futuro).

Spanish media related the movement to the 2008–2014 Spanish financial crisis, the Arab Spring, as well as demonstrations in North Africa, Iran, Greece, Portugal, and Iceland. The movement was also compared to Stéphane Hessel's political manifesto Time for Outrage!, which was seen to empower Spanish youth who were not in education, employment, or training (NEET). Protestors rallied against high unemployment rates, welfare cuts, politicians, and the two-party system in Spain, as well as the political system, capitalism, banks, and public corruption. Many called for basic rights, of home, work, culture, health, and education. The movement transferred to Europe the model of the protest camp which had been formed in the Arab Spring, adapting it to a more countercultural framework. This would later expand until influencing the creation of Occupy Wall Street.

According to RTVE, the Spanish public broadcasting company, between 6.5 and 8 million Spaniards participated in these events.

Since the 2008–2014 Spanish financial crisis began, Spain has had one of the highest unemployment rates in Europe, reaching a eurozone record of 21.3%. The number of unemployed people in Spain stood at 4,910,200 at the end of March 2011, up about 214,000 from the previous quarter, while the youth unemployment rate stands at 43.5%, the highest in the European Union. In September 2010 the government approved a sweeping overhaul of the labour market designed to reduce unemployment and revive the economy. Large trade unions such as CCOO and Unión General de Trabajadores (UGT), among other minor ones, rejected the plan because it made it easier and cheaper for employers to hire and fire workers. Trade unions called for the first general strike in a decade, on 29 September 2010.

For the rest of the year, the government proceeded with economic reforms. In January 2011, the government reached an agreement with the main trade unions to increase the retirement age from 65 to 67. Anarcho-syndicalist and other related unions rejected the plan and called for a strike on 27 January in Galicia, Catalonia and the Basque Country. Other demonstrations in Madrid ended up in altercations with the police. The majority of Spaniards also rejected the higher retirement age. In February a wide-sweeping internet copyright infringement policy known as the Sinde law passed, adding another motivation for the protests. The law allowed an administrative commission to shut down any website that showed links or allowed irregular downloading of copyrighted content without judicial supervision. Users on Spanish forums and social networks criticized the law; the PSOE, PP and Convergence and Union affirmed these criticisms. An anonymous campaign with the #nolesvotes appeared online, calling on citizens to vote against any of the parties that passed the law.

Prior to 15 May, other demonstrations served as precursors to the main protests in Madrid. These demonstrations include the 7 April protest in Madrid by the student group Youth without Future (Juventud Sin Futuro), which gathered 5,000 people. Spanish media drew comparisons between the demonstrations and the 2008–09 protests against the Bologna Process. The anti-austerity movement in Portugal also inspired the demonstrations undertaken in Spain. According to Peter Gelderloos, the movement led to the creation of hundreds of police-free zones across the country, hospitals were occupied and saved from privatisation, neighbourhood assemblies sprang up, unused land and homes were occupied and squatted, worker cooperatives were founded and urban community gardens were established.

In January 2011, users on Spanish social media networks and forums created the digital platform ¡Democracia Real YA!. Using Twitter and Facebook, it called "the unemployed, poorly paid, the subcontractors, the precarious, young people..." to take to the streets on 15 May in the following places: A Coruña, Albacete, Algeciras, Alicante, Almería, Arcos de la Frontera, Badajoz, Barcelona, Bilbao, Burgos, Cáceres, Cadiz, Cartagena, Castellón, Ciudad Real, Córdoba, Cuenca, Ferrol, Figueres, Fuengirola, Gijón, Granada, Guadalajara, Huelva, Jaén, Lanzarote, La Palma, León, Las Palmas de Gran Canaria, Lleida, Logroño, Lugo, Madrid, Málaga, Menorca, Mérida, Monforte de Lemos, Murcia, Ourense, Oviedo, Palma, Pamplona, Plasencia, Ponferrada, Puertollano, Salamanca, San Sebastián, Santa Cruz de Tenerife, Santander, Santiago de Compostela, Seville, Soria, Tarragona, Toledo, Torrevieja, Ubrique, Valencia, Valladolid, Vigo, Vitoria and Zaragoza. That same day, small demonstrations in support of the Spanish ones were organised in Dublin, Lisbon, Amsterdam, Istanbul, Bologna, London and Paris.

Before the demonstrations, ¡Democracia Real YA! staged several symbolic events, such as the occupation of a bank in Murcia on 13 May.