1922, Siqueiros returned to Mexico City to work as a muralist for Álvaro Obregón’s revolutionary government. Then Secretary of Public Education José Vasconcelos made a mission of educating the masses through public art and hired scores of artists and writers to build a modern Mexican culture. Siqueiros, Rivera and José Orozco worked together under Vasconcelos, who supported the muralist movement by commissioning murals for prominent buildings in Mexico City. Still, the artists working at the Preparatoria realized that many of their early works lacked the "public" nature envisioned in their ideology. In 1923 Siqueiros helped found the Syndicate of Revolutionary Mexican Painters, Sculptors and Engravers, which addressed the problem of widespread public access through its union paper, El Machete. That year the paper published – "for the proletariat of the world" – a manifesto, which Siqueiros helped author, on the necessity of a "collective" art, which would serve as "ideological propaganda" to educate the masses and overcome bourgeois, individualist art.
Siqueiros hoped to create a style that would bridge national and universal art. In his work as well as his writing, Siqueiros sought a social realism that at once hailed the proletariat peoples of Mexico and the world while avoiding the clichés of trendy "Primitivism" and "Indianism" 1932 at the Italian Hall at Olvera Street in Los Angeles.[11] Painting fresco on an outside wall – visible to passersby as well as intentional viewers – forced Siqueiros to reconsider his methodology as a muralist. He wanted the image – an image of an Indian peon being crucified by American oppression – to be accessible from multiple angles. Instead of just constructing “an enlarged easel painting,” he realized that the mural “must conform to the normal transit of a spectator.”[8] Eventually, Siqueiros would develop a mural technique that involved tracing figures onto a wall with an electric projector, photographing early wall sketches to improve perspective, and new paints, spray guns, and other tools to accommodate the surface of modern buildings and the outdoor conditions. He was unceremoniously deported from the United States for political activity the same year.
Creative and innovative, always interested in new techniques and materials, Siqueiros frequently used pyroxylin, a substance related to gun-cotton, which dries with amazing speed
INFLUENCES ON HIS ART: According to Philip Stein, author of the book Siqueiros: His Life and Works, states “What more profoundly affected Siqueiros as a young boy was his first exposure to art - the religious paintings hanging in the school.”2 Balochie noted that Siqueiros’ style was influenced by Michelangelo: “his work contains the powerful, foreshortened figures characteristic of Michelangelo and the bold perspective of Baroque art throughout his career.”3 Siqueiros derived his love of the modern age from the Italian Futurist, incorporating his love of speed, machines and technology into his work. Siqueiros was also influenced by the ideas of Dr. Atl, Director of the Academy of San Carlos in Mexico City, who encouraged him to join the military and political struggle of the Mexican Revolution. He did join the military, and in two years was attained the rank of second captain. From 1919 to 1922, he traveled in Europe where he studied and visited museums in Belgium, France, Italy, and Spain: there he became friends with Diego Rivera.

SOCIAL AND POLITICAL ASPECTS: Siqueiros was influenced by Marxism as evident from his concern towards class struggle. He admired both the workingman and modern technology. Rochfort Desmond, author of the book Mexican Muralists, states “The murals represent a people’s roots, their ethnicity, their shared sense of origin, in which the examination and re-appropriation of history can focus on the struggles for freedom, liberty, justice and, above all, identity.”1 One of Siqueiros’s purposes was to communicate to the people about the civilization and the history of the Mexican people.

Since Siqueiros was young he was involved in politics and social struggle. In 1911, when Siqueiros when he was young and was attending the Academy of San Carlos, he joined in his first political strike with other students in which they forced the director, Antonio Rivas Mercado to resign because of the unfair teaching methods. Siqueiros served his first ever sentence for throwing rocks at the director. He was subsequently arrested seven times for political beliefs and actions. In 1914 he stopped his studies, and when he was 17 he joined the Constitutionalist Army on the side of the Revolution.

Siqueiros included a great deal of social content in his work and in becoming a painter he was inspired by the ideas and experiences of the Revolution.1 He even joined a radical discussion group, which was made up of all painters who once served in the Revolution. This group were called Centro Bohemio and held meetings to confer about the purpose and directional path of art in the Revolutionary Mexican Society. Throughout the post-war period, Siqueiros’ political and artistic ideas between the 1920s and 1930s included a close relation between social revolution and modern technology.1 In the 1930s, he expressed his revolutionary political message using what he viewed as equally revolutionary technical means from modern technology, such as the spray gun, nitrocellulose pigments, and photography for mural producion.4 Siqueiros was named Executive Secretary of the Mexican Communist Party. Most of his works involved his political and social concerns and included figure forms that represented the revolutionary struggles towards freedom in the 19th century and also towards modern advancement.