[2] He graduated from the University of Wisconsin–Madison in 1922 where he was a member of Sigma Pi fraternity and Phi Beta Kappa.
[3] He later received his masters and doctoral (1928) degrees in history from Harvard University.
[3] He began his career as a history professor and archivist at the University of Virginia, and later worked as an archivist at the College of William and Mary and for Colonial Williamsburg.
[3] He was deeply involved professionally, and helped found the Society of American Archivists (SAA) and the Association for Documentary Editing (ADE).
[6][7] At the end of his career, Cappon became a research fellow at the Newberry Library in Chicago.