Craig-Martin moved to America at about age 6 and lived in Washington, D.C. He studied fine arts at Yale and became a senior tutor at Goldsmiths College in London, where he taught a younger generation of British artists, helping to launch several careers. He continues to exhibit his work.
"An Oak Tree" is Craig-Martin's most recognizable work. Created in 1973, it consists of a glass of water on a glass shelf, accompanied by a piece of text explaining that the work is an oak tree that looks like a glass of water. The original is on display in the National Gallery of Australia, and an artist's copy is in the Tate Modern. Recognized as a turning point in conceptual art, "An Oak Tree" is said to "question the nature of reality."
Many of the Young British Artists attended Goldsmiths College, where Craig-Martin taught. They rose to fame in the 1990s with artist-curated shows and were known for their shocking work, which often used dead animals and trash. The group was led by Damien Hirst and Tracey Emin.
Craig-Martin's later work often involved household objects and contained references to modern art, including Dada. He has been a trustee of the Tate Gallery and the National Art Collections Fund.
Craig-Martin's first retrospective was held in London's Whitechapel Gallery in 1989. Another retrospective, held in 2006 at the Irish Museum of Modern Art, showed 40 years of work, with more than 50 paintings, sculptures and conceptual and digital works.