[3][4] In 1943, he entered the Escuela Nacional de Artes Plásticas where he learning basic engraving with Carlos Alvarado Lang and fresco painting with Alfredo Zalce.[1][4] Beltrán was one of the most prolific, versatile and successful graphic artists in Mexico in the 20th century, as an illustrator, cartoonist, designer, founder of newspaper and magazines and engraver.There he created engravings with themes nationalism, the Mexican Revolution, social criticism and peace working with artists such as Leopoldo Méndez, Pablo O'Higgins, Adolfo Mexiac, Fanny Rabel, José Chávez Morado, Celia Calderón, Elizabeth Catlett, Andrea Gómez and Mariana Yampolsky.[4] One early piece is a relief in the upper part of the Pulmonology Institute of the Centro Médico Nacional Siglo XXI in 1959 collaborating with Francisco Zúñiga.In 1967 he created the mural Quetzalcóatl y el hombre hoy done in mosaic tile, snail shells and ceramics for the exterior of the Xalapa Museum of Anthropology, Veracruz.It produces books, pamphlets, newsletters, field notes and various other documents which are contained in its Archivo de la Traditiones y Arte Popular.[5] One of his drawings, that of Benito Juárez entering Mexico City, was exhibited for decades in the Zocalo metro station as a mural, but misattributed to “an unknown artist of the last (19th) century.” Beltrán comment this was that he wished he had lived in the 19th century instead of the 20th.[2] A large quantity of his work, probable the largest collection of his to exist, was donated by the artists to UNAM, which the university edited into a book in 2003 called Alberto Beltrán, 1923-2002 Cronista e Ilustrador.The book also included essays by Vicente Quitarte, Ernesto de la Torre Villar, Silvia González and Elena Poniatowska.[5] He's considered to be part of the Escuela Mexicana de Pintura, with his work featuring realistic and detailed facial expressions, which often told much of the story.These were used to illustrate publications such as literature published by the Instituto Nacional Indigenista and a book called Relatos, mitos y leyendas de la Chinantla by Roberto Weitlaner.[2] He often drew depictions of common men such as street vendors, cooks, bakers, police and many others along with symbols such as the nopal cactus, maguey, huaraches, machetes, sombreros and sarapes.