Jules Langsner was born Julius Harold Langsner in New York, New York on May 5, 1911. His family later relocated to Ontario, California around 1922 to start a small farm. The farm soon transformed into the Paradise Health Resort and became a place frequented by intellectuals and their families. In Ontario, he was introduced to the Pollock family, and became friends with three of their sons: Jackson, Frank, and Sanford. Langsner attended Belmont High School in Los Angeles, Calif., while many of his friends attended Manual Arts High School (also in Los Angeles). In his late teens, he became an advocate for modernist painting styles, including abstraction and surrealism. Langsner, then a budding poet, spent much of his time in Los Angeles as part of a young intellectuals group that included Phillip Goldstein (later known as Philip Guston), Jackson Pollock, Reuben Kadish, Frank Pollock, Sanford Pollock (later known as Sande McCoy), Leonard Stark, and Don Brown. When they weren't working odd jobs, Langsner and his leftist circle debated politics, philosophy and art. He was greatly affected by racism and anti-immigration and became interested in education and justice from a young age. He became interested in avant-garde painting while Kadish, Pollock and Guston were being mentored by Los Angeles artist Lorser Feitelson. Feitelson introduced the young men to post-surrealism, pastiche and film noir influences through his work.
Langsner enrolled at the University of California, Los Angeles as a psychology major, then enlisted in the Army in 1944 as a social worker revising Rorschach psychodiagnostic charts. He remained in the United States for the duration of World War II. After WWII, Langsner continued to develop his professional and personal relationships in Los Angeles. He befriended a variety of artists and intellectuals, including artist and printmaker June Wayne, who would remain a dear friend until his death.
His curiosity and appreciation for art and artists in Los Angeles led him to pursue art writing and criticism. In 1948, Langsner published his first article in Art & Architecture, contributing periodically until 1963. Langsner's writing brought national attention to local artists, institutions, and topics. He promoted the Los Angeles County Museum of Art and other local art museums in multiple publications. In the April 1963 issue of Art in America, Langsner coined the phrase "second city" to describe Los Angeles in comparison to New York's art scene. In 1951, he published one of the first articles to embrace Simon Rodia's towers in Watts as a work of art. He promoted many artists, including Rico Lebrun, William Turnbull, Sam Francis, and Matsumi Kanemitsu. His ability to communicate with and befriend artists, as well as his ability to understand the subtleties of multiple styles, led him to pursue art curatorship. In 1957, Langsner was sponsored by the Ray Cardillo Travel Agency to visit art centers throughout Europe, and curated a Marc Chagall exhibit at the Pasadena Art Museum. Perhaps he is best known for curating the landmark exhibition "Four Abstract Classicists" in 1959, which included work by John McLaughlin, Frederick Hammersley, Karl Benjamin and Lorser Feitelson. It was in 1959 that Langsner and art historian Peter Selz originated the phrase "hard-edge painting" to describe the colors, shapes and style of abstract expressionist painting on the West Coast. His catalog for the exhibit became the criterion for the hard-edge school of painting. In 1961, Langsner was awarded a fellowship grant for advanced study in the fine arts from the Graham Foundation, and in 1964 was the recipient of a Ford Foundation grant for visual arts research. While traveling for his Ford grant, Langsner was in close correspondence with June Harwood, a hard-edge painter and in 1965, they were married. In 1966, Langsner organized and curated the first full-scale retrospective of Man Ray in the United States for the Los Angeles County Museum of Art, establishing him as the pre-eminent art critic of the West Coast. Langsner died suddenly of a heart attack on September 29, 1967.