Bill Siavelis grew up in Chicago and attended Austin High School on the city's west side. He received his bachelor's and master's degrees in history from DePaul University (1963) in Chicago. He taught fifth grade in Morton Grove, Illinois, for four years before becoming a teacher of history at Evanston Township High School for thirty-two years.
In 1970, while taking further course work at NIU during a sabbatical leave, he began to supervise student teachers for the History Department, and has been doing so ever since then. Bill thoroughly enjoyed being both an active teacher and a university supervisor during his years at Evanston, and continues to take pleasure in supervising student teachers as a retired teacher.