Returning to the States after the year and was named assistant dean of education (for freshmen) at Harvard University.
During World War II, Keppel was secretary of the Joint Army-Navy Committee on Welfare and Recreation in Washington, D.C.
During his fourteen years as dean, the School of Education more than quadrupled in size, applications increased tenfold, and the endowment swelled to over $9 million.
He was a widely respected leader nationally as well, serving on a number of important committees, task forces and councils."
Keppel was widely respected as a national leader and served on numerous committees, task forces, and councils during his tenure.
He was an aggressive advocate for civil rights and was the principal architect of the Elementary and Secondary School Act of 1965(ESEA).
He later served as vice chair of the New York City Board of Higher Education and director of the Aspen Institute.