There is little information written about the life of Van Regenmorter prior to his political career. The biographical sketches published by the state of Michigan contain what little is written about his life before his election to the State House of Representatives in 1982. These include The Michigan Manual of 1983-84, 1987–88, and 2001–2002. All of which state his date of birth, January 29, 1939 in Jamestown Michigan. His obituary in the Grand Rapids Press also contains this information along with the names of his parents, William Sr. and Zora (Van Oss) Van Regenmorter. Following his birth no other information is provided until mention of his schooling, which took place at Calvin College. There is another lapse in biographical information between his time at Calvin College and his professional career. Capitol Profiles states that William was a financial analyst for Dun & Bradstreet and at one point he was the owner of a retail furniture store. It is documented in the 1983-84 edition of the Michigan Manual that Van Regenmorter was a member of the Christian Reformed Church.