He was selected as a first-team All-American at the guard position three consecutive years while leading Harvard University to three undefeated seasons from 1912 to 1914.

[3] In helping Harvard win three straight national championships, Pennock was also selected as a first-team All-American in all three years by Walter Camp.

[9] While attending Harvard, Pennock was also a member of the Delta Kappa Epsilon fraternity, the Institute of 1779, and the Hasty Pudding Club.

[2] He entered into a business partnership with two other Harvard graduates, James Bryant Conant and Chauncey Loomis,[11] and formed the LPC Laboratories.

Pennock and his partners opened a plant in a one-story building in the Queens section of New York, at which they manufactured chemicals that were selling at high prices due to interruption of imports from Germany during World War I.

[1][12] His teammate Walter Trumbull spoke at the funeral and reflected on Pennock's life: Stan was a true man.