Mexican muralism refers to the art project initially funded by the Mexican government in the immediate wake of the Mexican Revolution (1910–1920) to depict visions of Mexico's past, present, and future, transforming the walls of many public buildings into didactic scenes designed to reshape Mexicans' understanding of the nation's history. The murals, large artworks painted onto the walls themselves had social, political, and historical messages. Beginning in the 1920s, the muralist project was headed by a group of artists known as "The Big Three" or "The Three Greats". This group was composed of Diego Rivera, José Clemente Orozco and David Alfaro Siqueiros. Although not as prominent as the Big Three, women also created murals in Mexico. From the 1920s to the 1970s, murals with nationalistic, social and political messages were created in many public settings such as chapels, schools, government buildings, and much more. The popularity of the Mexican muralist project started a tradition which continues to this day in Mexico; a tradition that has had a significant impact in other parts of the Americas, including the United States, where it served as inspiration for the Chicano art movement.

Mexico has had a tradition of painting murals, starting with the Olmec civilization in the pre Hispanic period and into the colonial period, with murals mostly painted to evangelize and reinforce Christian doctrine. The modern mural tradition has its roots in the 19th century, with this use of political and social themes. The first Mexican mural painter to use philosophical themes in his work was Juan Cordero in the mid-19th century. Although he did mostly work with religious themes such as the cupola of the Santa Teresa Church and other churches, he painted a secular mural at the request of Gabino Barreda at the Escuela Nacional Preparatoria (since disappeared).

The latter 19th century was dominated politically by the Porfirio Díaz regime. This government was the first to push for the cultural development of the country, supporting the Academy of San Carlos and sending promising artists abroad to study. However, this effort left out indigenous culture and people, with the aim of making Mexico like Europe. Gerardo Murillo, also known as Dr. Atl, is considered to be the first modern Mexican muralist with the idea that Mexican art should reflect Mexican life. Academy training and the government had only promoted imitations of European art. Atl and other early muralists pressured the Diaz government to allow them to paint on building walls to escape this formalism. Atl also organized an independent exhibition of native Mexican artists promoting many indigenous and national themes along with color schemes that would later appear in mural painting. The first modern Mexican mural, painted by Atl, was a series of female nudes using "Atlcolor", a substance Atl invented himself, very shortly before the beginning of the Mexican Revolution. Another influence on the young artists of the late Porfirian period was the graphic work of José Guadalupe Posada, who mocked European styles and created cartoons with social and political criticism. Critiquing the political policies of the Díaz dictatorship through art was popularized by Posada. Posada influenced muralists to embrace and continue criticizing the Díaz dictatorship in their works. The muralists also embraced the characters and satire present in Posada's works.

The Mexican Revolution itself was the culmination of political and social opposition to Porfirio Díaz policies. One important oppositional group was an intellectual community that included Antonio Curo, Alfonso Reyes and José Vasconcelos. They promoted a populist philosophy that coincided with the social and political criticism of Atl and Posada and influenced the next generation of painters such as Diego Rivera, José Clemente Orozco and David Alfaro Siqueiros.

These ideas gained power as a result of the Mexican Revolution, which overthrew the Díaz regime in less than a year. However, there was nearly a decade of fighting among the various factions vying for power. Governments changed frequently with a number of assassinations, including that of Francisco I. Madero who initiated the struggle. It ended in the early 1920s with one-party rule in the hands of the Álvaro Obregón faction, which became the Partido Revolucionario Institucional (PRI). During the Revolution, Atl supported the Carranza faction and promoted the work of Rivera, Orozco and Siqueiros, who would later be the founders of the muralism movement. Through the war and until 1921, Atl continued to paint murals among other activities including teaching the Mexico's next generation of artists and muralists.

In 1921, after the end of the military phase of the Revolution, General Alvaro Obregón rose to power. In the aftermath of the Revolution, Mexico had entered a transition from an "oligarchic" state to a "modernizing" state, one that favored urbanization and the bourgeoisie citizens of society. As the country underwent this reformation, General Obregón realized that the reconstruction of a post-revolution Mexico would require a comprehensive alteration of symbols associated with Mexican identity on both cultural and political grounds.

Shortly after the wars end, Obregón appointed José Vasconcelos to act as the Secretaría de Educación Pública, or Minister of Public Education. In his efforts to help raise a sense of nationalism and promote the inclusion of the masses in political and social ideologies, it was Vasconcelos' idea to have a government-backed mural project. His time as secretary was short but it set how muralism would develop. His image was painted on a tempera mural in 1921 by Roberto Montenegro, but this was short lived. His successor at the Secretaría de Educación Pública ordered it painted out.

Parallel to the utilization of murals during the pre-Hispanic and the colonial period, the murals were not to simply satisfy aesthetic purposes, but to promote certain social ideals in the Mexican people. These ideals or principles were to glorify the Mexican Revolution and the identity of Mexico as a mestizo nation. This placed great emphasis on the pride associated with the indigenous culture of Mexico. The government began to hire the country's best artists to paint murals, calling some of them home from their time in Europe, including Diego Rivera. These initial muralists included Dr. Atl, Ramón Alva de la Canal, Federico Cantú and others but the main three artists that spearheaded the muralist project were David Alfaro Siqueiros, José Clemente Orozco and Diego Rivera. These three artists, commonly known as "Los Tres Grandes", claimed to act as both the "'voice and vote' of the Mexican national consciousness," calling themselves "guardians of the national soul". The muralists differed in style and temperament, but all believed that art was for the education and betterment of the people. This was behind their acceptance of these commissions as well as their creation of the Syndicate of Technical Workers, Painters, and Sculptors.