Karras was a graduate assistant at the University of Minnesota in 1991 and at Northern Illinois University in 1992. He then worked as a defensive coordinator at Lake Forest College from 1993 to 1994 and as a defensive line coach at the University of St. Francis in 1995. In 1996, Karras became the head football coach for Andrean High School in Merrillville, Indiana, and took his team to the state championship, where they lost to Bishop Chatard High School of Indianapolis. In 1999, Karras moved on to Saint Xavier University in Chicago as offensive coordinator. After four years at Saint Xavier, Karras moved to Terre Haute, Indiana to become head football coach at Rose–Hulman Institute of Technology. In 2006, Karras took the job of coaching the inaugural football team at Marian University.