In 1911 Eileen Agar’s parents left Argentina for London. She studied at the Byam Shaw School of Art in 1919, then at the school of the painter Leon Underwood (1890–1975), at the Slade School of Fine Art from 1925 to 1926, and then in Paris from 1928 to 1930. In 1926 she met the Hungarian writer Joseph Bard. In 1928 they moved to Paris, where she became friends with André Breton and Paul Éluard. In 1936 she exhibited three canvases, including Quadriga, and five other works at the International Surrealist Exhibition in London. In 1937 she took a trip to Mougins with Paul and Nusch Éluard, Picasso and Dora Maar, Roland Penrose and Lee Miller, who made a portrait of her. Through 1940, she participated in Surrealist exhibitions hosted in Amsterdam, New York, Paris, and Tokyo. Associated with this movement for her singular connections between objects and images, she nevertheless stood out because of a certain sense of rigour, far removed from the spontaneous expression of the subconscious.

After the Second World War, E. Agar began a new, very productive period: 16 personal exhibitions between 1946 and 1985. Her work especially showed stylistic affinities with cubism and collage. The paintings consisted of flat, cut-out zones of colour arranged into portraits or landscapes, especially on maritime themes. She became a member of the London Group beginning in 1933 and her work was chosen by R. Penrose and Herbert Read for the International Surrealist Exhibition at the New Burlington Galleries in 1936. She then began exhibiting alongside the Surrealists, in England and abroad. Beginning in 1936, she experimented with new automatic techniques and new materials, taking photographs and creating collages and objects. During the 1960s, she made dab paintings featuring surrealist elements.