Growing up in Sunnyside, Queens, Fortgang’s earliest experiences with art were in making handicrafts as a child. She attended Buck’s Rock Work Camp and Saturday painting classes with Phoebe Helman. Even into her career, the artist continued to knit, crochet, and make bargello, tactile modes of creating visual works. She studied painting at Queens College with Louis Finkelstein and, buoyed by his encouragement, applied to Yale’s School of Art & Architecture, where she would earn a BFA in 1966 and MFA in 1968. Early on, the artist made action paintings. At Yale, Fortgang studied with eminent artists like Jack Tworkov and Al Held alongside fellow students including Howardena Pindell, Fred Sandback, and William Conlon. Fortgang had the freedom to create divergent bodies of work, generating rich explorations of color, exploitations of the grid, and systems of drips that have anchored her work in later decades. In the late 1960’s, Fortgang created a series of paintings with technicolor palettes, biomorphic forms, and a heart motif. As the artist recalls, these works were done at a time when she was falling in love (with a fellow Yale MFA candidate, whom she remains married to). These paintings capture the excitement of that moment, undergirded by a logic of abstract shapes seemingly gravitating towards one another in companionship.

In the 1970’s, Fortgang began using acrylic paint, creating work focused on systems. Using her experiences with knitting, crochet, and Bargello, she used these works to explore process, thinking about how each choice would affect the final painting. Taping off various elements, Fortgang created works focused on the grid. Her work of the mid-1970’s includes drips reminiscent of her earlier action painting, but by the end of the decade, she started to use only hard-edge lines to create works that look like weavings. Her work from this period was included in the important Pattern Painting exhibition, curated by John Perrault at P.S.1 in 1978. Fortgang has showed in important venues for contemporary art including the Aldrich Museum, Ridgefield, CT and the Whitney Museum of American Art, New York. In 2025 the gallery hosted Susan Fortgang's first solo exhibition, Susan Fortgang: The Spaces in Between, which was reviewed by The New York Times.