In 1950 he became one of the nation's youngest head coaches at a major college when he took over the coaching job at Fordham. He spent 18 years there, taking seven Ram teams to post-season tourneys, before starting a long and successful coaching career at Penn State, where he joined three former Brown friends: Rip Engle, Joe Paterno, and Joe McMullen. Bach would later coach the Golden State Warriors for over three years. He served as an interim coach briefly in 1980, and then as the full-time coach from 1983 to 1986. In 1986 Bach joined the Chicago Bulls as an assistant. After the team won three straight championships from 1991 to 1993, Bach moved on to coaching jobs with the Charlotte Hornets, Detroit Pistons, and Washington Wizards. He returned to the Bulls in 2003, and retired in 2006.
After retiring from basketball, Bach turned to painting. In 2007, thirty-two of his watercolors were put on display at the Sevan Gallery in Skokie, Illinois.
National champion Postseason invitational champion Conference regular season champion Conference regular season and conference tournament champion Division regular season champion Division regular season and conference tournament champion Conference tournament champion