Bayh was the lead sponsor of the landmark 1972 law prohibiting gender discrimination in education -- known as Title IX for its section in the Higher Education Act.
The law's passage came at a time when women earned fewer than 10 percent of all medical and law degrees and fewer than 300,000 high school girls -- one in 27 -- played sports.
Tennis great Billie Jean King, who worked with Bayh on women's rights issues, released a statement with his family Thursday saying the former senator was "one of the most important Americans of the 20th century."
Bayh won his first election to the state Legislature in 1954; his son Evan was born the following year.
He earned a law degree from Indiana University, completing law school while serving in the Legislature.