Oliver Wolcott was born in Windsor, Connecticut as the youngest of fourteen children of the Royal Governor Roger Wolcott. He attended Yale College, graduating in 1747. He was commissioned to raise a militia company to fight in the French and Indian War, and he served the King as Captain in this unit on the northern frontier. At the end of the war, Wolcott studied medicine, then was appointed sheriff of the newly created Litchfield County, Connecticut, serving from about 1751 to 1771.