Sundheim graduated with Honors and Distinction in Economics from Stanford University in 1975. His Honors Thesis was on campaign finance reform. Sundheim also earned two varsity letters on the Stanford football team. While at Stanford Sundheim ran “Volunteers for Youth,” a program that matched Stanford athletes with children with self-esteem issues. The program was so successful that upon graduation Sundheim and Chris Avery took the program national, eventually having programs at 54 campuses across the country. Sundheim earned his Juris Doctorate from Northwestern University in 1980 with the aid of an Exceptional Student Fellowship. While at Northwestern, Sundheim interned for a federal judge and the Better Government Association. Upon graduation from law school, Sundheim joined the Silicon Valley law firm of Ware, Fletcher and Freidenrich. In 1986 Sundheim and former Stanford classmate Stan Doty formed Doty & Sundheim. Sundheim served as President of the firm until 2001. In September 2015, Sundheim announced that he would run for the U.S. Senate seat being vacated by Senator Barbara Boxer. Sundheim has been married for over 32 years to Cheryl Sundheim. They have two adult children and live near Palo Alto, California.