In 1760, after further studies at the College of New Jersey (now Princeton University), Rush graduated with a Bachelor of Arts degree at age fourteen. From 1761 to 1766, Rush apprenticed under Dr. John Redman in Philadelphia. Redman encouraged him to further his studies at the University of Edinburgh in Scotland, where Rush studied from 1766 to 1768 and earned an M. D. degree. Rush became fluent in French, Italian, and Spanish as a result of his studies and European tour. While at Edinburgh, he became a friend of the Earl of Leven and his family, including William Leslie.