Brother Thomas W. Spalding entered the Xaverian Brothers in 1942. In 1948 he obtained a B.A. from Catholic University (Phi Beta Kappa), an M.A. from Fordham in 1957, and Ph.D. in history from Catholic University in 1971.

From 1948 to 1957 Brother Spalding was a teacher at Cardinal Hayes High School. He taught at Xaverial College from 1957 to 1970, and has taught at Spalding University from 1970 to present.

In 1973, Brother Spalding published Martin John Spalding: American Churchman, for which he received the annual John Gilmary Shea award of the American Catholic Historical Association in 1974.

In 1989, he published The Premier See: A History of the Archdiocese of Baltimore for which he received the biennial award for the best book on Maryland History from the Maryland Historical Society in 1990.

In 1994 Brother Spalding published St. Vincent de Paul of Baltimore: The Story of a People and Their Home.

He has also published some fifty articles or reviews for learned journals or encyclopedias. He is presently working on a history of frontier Catholicism which will include the story of the Maryland Catholics who settled Nelson County and other parts of central Kentucky.