Born in New York, New York, she went to a cattle call for the film Joe in 1970 with her then-husband Chris Sarandon, and, although Chris did not get a part, Susan received the major role of the disaffected teen who disappears into the seedy underworld. She did not follow up on the success of that movie, however, and it was five more years before she appeared in The Rocky Horror Picture Show, the cult classic. That same year, she played the female lead in The Great Waldo Pepper, opposite Robert Redford.
Even then, it was not right away that she became a star. She was nominated for an Oscar in 1980 for Atlantic City, but even then she did not become a household name. That took 1988's Bull Durham. It was while filming that movie that she met actor Tim Robbins, with whom she established an unmarried relationship that continues.