After attending the Francestown Academy for three terms he began teaching at the age of seventeen. At this time the movement to found a college had just begun among the Universalists, and the young schoolmaster, who wished to enter the new institution, preferred carrying on his studies by himself until its opening to matriculating at any other college. So he continued to support himself by teaching, studying early and late, meanwhile, upon his Latin and Greek, until 1855, when he entered Tufts as a Junior. Two years later he graduated as Valedictorian of the first class to receive degrees from the college.

Before completing his college course he obtained a position as teacher in Arlington, which he was allowed to hold while still continuing his work at the Hill. After teaching in Arlington for three years he was appointed to the principalship of Clinton Liberal Institute, where he remained until 1864, when he was tendered the professorship of Latin at Tufts. Since then he has been actively engaged at the college, not only in the work of his department, but also as Secretary of the Faculty until 1894, and since that time as Registrar. He performed the functions of the latter office for many years prior to its formal creation, acting also as assistant to the college Treasurer until the appointment of Rev. W. A. Start as Bursar in 1895.

Professor Dearborn was married, March 24, 1858. In 1878 he spent several months in travelling with his wife through England, France, Germany, and Italy, and made quite an extensive collection of Roman photographs and relics, with which he often entertains his classes in Roman antiquities.

Professor Dearborn has recently founded a scholarship known as the Scholarship of the Class of 1857, for the benefit of women students. He is devoted to his Alma Mater, and has always labored earnestly for her welfare.