Born in Ipswich, Massachusetts, Cogswell received a grammar school education in Ipswich, and attended Phillips Exeter Academy.[1] He graduated from Harvard in 1806, and studied law from 1807 to 1809.[1] After making a voyage to India as supercargo of the vessel in which he sailed, Cogswell studied law with Fisher Ames in Dedham,[2] and practised for a few years in Belfast, Maine. In 1812 he married Mary, the daughter of Gov. John Taylor Gilman. She died in 1813.