Spencer BonaventureTracy was born April 5, 1900 in Milwaukee, Wisconsin. His father John Tracy was Irish; his mother Caroline Brown Tracy could trace her ancestors back to American Colonial days. Spencer also had a brother, Carroll, older by four years.

Young Spencer did not enjoy school and wanted to quit to find a job when he was sixteen. The plan was quickly vetoed by his parents, so Spencer enrolled at Marquette Academy. However, when America entered World War I in 1917, he saw his chance to "get out of school once and for all, pack up and get right smack into the middle of a lot of excitement." He joined the Navy, was sent to Norfolk Navy Yard in Virginia, and was still there when the war ended. So much for excitement.
With no specific plans upon his discharge, Tracy decided to take advantage of servicemen's education benefits and enrolled at Ripon College as a pre-med student. He joined the debating team and to his vast surprise enjoyed it immensely. Acting in school plays was the next logical step, and Tracy's first performance was a leading role, earning him praise in the school newspaper as an "unusually strong actor" with

adiness...strength, and suppressed emotion."

Tracy was soon considering acting as a career, and auditioned at the Sargent school in New York. His father agreed to pay the tuition for the first semester, although he proclaimed that this acting "sounded like a silly idea." Tracy took a room in a lodging house. His roomate was another Sargent student, by the name of Pat O'Brien. The two survived on 30 dollars a month, and a frequent diet was pretzels and water. Tracy later said he studied dramatics "like I'd never studied anything before in my life" - primarily because he was sure he wouldn't be able to afford to attend classes for very long, and wanted to learn all he could as fast as possible.