He was born c. 1785–1788, probably in New York City, and likely received his early training in portraiture from his father, whose naive style is reflected in the younger Earl's earliest works.
He traveled to London in 1809, where he studied for a year with John Trumbull and was advised by Benjamin West to learn perspective, anatomy, and three-dimensional illusion.
He remained in England until 1814, living with his maternal grandfather and uncle in Norwich and executing portrait commissions.
He then traveled to Paris before returning to the United States in December 1815 to create grand-scale history paintings on the European model.
[1] As preparation for a planned project depicting the Battle of New Orleans, Earl met General Andrew Jackson and visited him at his Tennessee home, The Hermitage, in January 1817.