Born in Lisbon, Maine, Lunt received his undergraduate degree from Bowdoin College in 1904, and his Ph.D from Harvard University in 1908 under the supervision of Charles Homer Haskins.
[3] Following World War I, he accompanied Woodrow Wilson and his Harvard mentor Haskins to the Paris Peace Conference, where he was the chief adviser to the American delegation on Italian affairs.
Lunt's primary scholarly interests focused on the fiscal administration of the papacy during the Middle Ages and its legal and economic relationship with the English church in particular.
In 1939, he produced The Financial Relations of the Papacy with England to 1327, published by the Medieval Academy of America, documenting the extensive system of religious revenues Rome raised from English foundations.
[11] At the time of his death, Lunt had completed the manuscript of a companion volume covering the period up to 1534, but it remained unpublished due to financial constraints.