Studied medicine with Dr. Thomas Bond. Member of the Philadelphia Medical Society (1766) and the American Philosophical Society. Trustee of the University of Pennsylvania. Senior Fellow and Treasurer of the Philadelphia College of Physicians (1787-90). Advocated temperance, prison reform, and the abolition of slavery; active in medical charities.
Son of Matthew and Cornelia (DePeyster) Clarkson; stepson of Gilbert Tennent. Brother of Matthew Clarkson. Married Mary Flower (1761); eight children. Prominent Anglican.