Stephen Mix Mitchell was born on December 9, 1743, at Wethersfield, Connecticut. He was the son of James Mitchell, a merchant and West-Indian trader who had emigrated about 1730 from Paisley, Scotland. Stephen was the only child of his father's second marriage. His mother, Rebecca, a first cousin of Jonathan Edwards, was a daughter of the Rev. Stephen Mix (Harvard, 1690), a native of New Haven and pastor of the First Church of Wethersfield.