Posthumus grew up on a dairy farm in Alto, Michigan, outside of Grand Rapids.

Posthumus joined Engler on as his running mate and candidate for lieutenant governor in 1998[4] and went on to serve in that post for four years.

On November 8, 2010, Governor-elect Rick Snyder named Posthumus to be his senior adviser and legislative lobbyist.

[7] Posthumus married Beth Ann (née Mihlethaler) Fogg on September 24, 2011.

[8] Dick's son, Bryan, is a Michigan state representative, and advocate for Alcoholic's Anonymous and Dick's daughter, Lisa, is a Republican member of the Michigan House of Representatives.