[2] Groesbeck attended the public schools of Mount Clemens, Michigan, and of Wallaceburg, Ontario, where his parents resided for two years with their family.

Groesbeck wanted to become a lawyer from an early age, and undertook the study of law in the office of an attorney at Port Huron, Michigan.

He was admitted to the bar that year and set up practice in Detroit where he rapidly gained the "respect, goodwill and confidence of his colleagues, because of his close conformity to the highest ethical standards of the profession".

[3] Groesbeck's entrance into state politics came in 1912 — he led efforts to select a delegation to the Republican National Convention favoring the renomination of President William Howard Taft.

As reported in The New York Times, Attorney General Groesbeck supported a call for Henry Ford to run for the United States Senate as a Republican.

[3] At the Detroit Club, he was instrumental in 1922 in selecting James Couzens to be the successful Republican candidate for the Senate seat left vacant by Truman Newberry.