Jack Jefferson, painter, printmaker, and teacher, was born on 2 December 1920 in Lead, South Dakota. Jefferson worked as a gold miner in the Homestake Mines from 1939 to 1940 to afford enrollment at the University of Iowa, where he studied from 1940 to 1942. He enlisted in the Marines and was part of the first wave of fighting at Guadalcanal.

After serving in World War II, Jefferson moved to San Francisco where he attended the California School of Fine Arts (now the San Francisco Art Institute). He was among twelve of the Clyfford Still’s students who founded the Metart Galleries, San Francisco’s earliest “alternative space” and where Jefferson held his first solo exhibition in 1949.

In Art in the San Francisco Bay Area 1945-1980, Thomas Albright wrote: "The work of “teacher-painters” such as Jack Jefferson and Alvin Light tended to gravitate toward the pole of Abstract Expressionism represented by [Frank] Lobdell. Jefferson, like Still was a native of the Dakotas who grew up on the great northern prairie. During his student years at the California School of Fine Arts, he was deeply impressed by certain aspects of Still’s painting, and his own early works took on some of these attributes: the convulsive, organic forms; the stark “sort of anti-color,” the “grays and blacks and red”; the intensity and “fervor” and “willingness to use something really raw and brutal.” …Jefferson’s painting in the late 1950s moved from an all-over complexity toward greater simplification, concentrating on what he called “a central image effect,” but he did not settle into any specifically identifiable vocabulary of forms. …His works were exhibited even less frequently than Lobdell’s; but his quietly forceful, uncompromising form of Abstract Expressionism, and his determined commitment to pursuing his own path, strongly influence many younger San Francisco painters."

In 1953, Jefferson was awarded an Abraham Rosenberg Fellowship for travel in the northwestern United States and British Columbia. In 1959, he joined the faculty of the California School of Fine Arts where he is remembered as a mentor to many artists. He retired from the school in 1978.

Jefferson had a solo exhibition at the M.H. de Young Memorial Museum in 1960, and was included in exhibitions at the San Francisco Museum of Modern Art in 1968 and 1976; the Whitney Museum Biennial Exhibition in 1975; the Smithsonian Museum in 1977; the Wiegand Gallery of the College of Notre Dame in 1989; and the Triton Museum of Art, the Laguna Art Museum, and the San Francisco Museum of Modern Art in 1996. A memorial retrospective was mounted at the San José Museum of Art in 2001.

Jefferson's work is represented in the collections of the Oakland Museum of California, the San Francisco Museum of Modern Art, and the San José Museum of Art.

Jack Jefferson died on 5 November 2000 at St. Francis Memorial Hospital in San Francisco, California.