Larkin was born in Medford, Massachusetts, the son of Charles Ernest Larkin, a collector and dealer of antiques, and Kate Mary Waterman. He had two brothers and a sister. He grew up in Medford, and later in Georgetown, Massachusetts, where in 1914 he graduated with honors from the Perley Free School. By this time he had already begun to show his interest in the arts. He enrolled in Harvard University where he majored in French and Latin. He received his B.A. in 1918. He won several scholarships as an undergraduate and was elected to Phi Beta Kappa in his senior year.