In 1929, McKenna graduated Phi Beta Kappa with a bachelor's degree in English literature from Pomona College.
He then earned his master's degree, with a thesis entitled "Naturalism of Thomas Hardy" at Claremont Graduate University in 1931.
He continued on to Harvard to pursue a Ph.D. but left in 1934, when he was called back to California during the Great Depression to manage the Pomona Pump Company, a family business in the Pomona Valley that made submersible pumps and marine engine parts.
[4] With cousin Charles McKenna, he bred Arabian horses, winning numerous medals at the Los Angeles County Fairgrounds in Pomona.
[2][4] McKenna played a key role in the founding of the school that later came to bear his name, first with his own money in 1944 and through fundraising.