Scully was born in Erie, Pennsylvania on September 17, 1960, to Hubert L. "Hoot" Scully and Elizabeth Jane North "Betty" Scully. He was the 14th of 16 children, including five sets of twins.
Scully received an undergraduate degree with honors in communication and political science from American University in Washington, D.C. During his degree he completed a study abroad program at the University of Copenhagen, interned for Sen. Joe Biden and served as a staff assistant in Sen. Ted Kennedy’s media affairs office. Scully then earned a Master of Science degree in journalism from Northwestern University’s Medill School of Journalism, graduating magna cum laude in 1985.
Scully began his journalism career as a weekend newscaster on WAMU, the American University-based radio station. Following his undergraduate degree, he worked as a reporter and anchor for Erie's WSEE-TV in 1982 and 1983. He returned to WSEE after completing his graduate studies in 1984. After a stint as a Washington, D.C.-based correspondent for WHBF-TV in Rock Island, Illinois, he joined WHEC-TV in Rochester, New York in 1986 as a correspondent covering business, politics and local government. He also taught courses on media and politics as an adjunct faculty member at Nazareth College and St. John Fisher College.
Scully joined C-SPAN in 1990 as political editor and White House producer. Since 1991, he has been responsible for coordinating campaign programming for C-SPAN, C-SPAN.org and C-SPAN Radio. As senior producer for the network's White House coverage, Scully manages a team of field producers responsible for coverage of the White House, politics and special projects. He serves as the regular Sunday host of Washington Journal, a live three-hour news and public affairs program. He is a host and moderator for a number of other C-SPAN programs, including Newsmakers, Road to the White House and In Depth on Book TV. In addition to his television work, he regularly appears on C-SPAN Radio’s Washington Today, a live two-hour afternoon drive time program broadcast nationwide on Sirius XM Radio.
In January 2003, Scully assumed the Amos P. Hostetter Chair at the University of Denver and Cable Center, teaching a distance learning course on media, politics and public policy issues via a cable television connection between Washington, D.C., University of Denver, Pace University and George Mason University. The class aired on C-SPAN and C-SPAN3, and was streamed via the C-SPAN website. He taught the course at the University of Denver until 2011. He continues to teach the class at George Mason University in conjunction with Purdue University and The Washington Center.
Scully served nine years on the Executive Board of the White House Correspondents' Association, and was elected by his peers to serve as president from 2006 to 2007. Until her death, Scully's mother accompanied him to most WHCA dinners throughout the administrations of Presidents Bill Clinton, George W. Bush, and Barack H. Obama.
According to Politico, Scully is known in the media for his "evenhandedness". He was the 2009 recipient of the Fitzwater Center for Communications Award, for exemplary journalism and public service, and in the same year was recognized by The Washingtonian as one of the capital's "50 Top Journalists". John Oliver has repeatedly referred to Scully as "The Most Patient Man on Television".
Scully and his wife, Kathryn R. "Katie" Scully, reside in Fairfax Station, Virginia. They have four children: Mary Cate, who is a midshipman at the United States Naval Academy, Danny, Cristen, and Natalie Cathleen, whom they adopted in 2009. Daniel attended Paul VI Catholic High School, and is now studying at James Madison University. Two others died in childhood, Carolyn in 1994 of sudden infant death syndrome (SIDS) and Jack, stillborn in 1996. Scully serves on the board of both the CJ Foundation for SIDS, which raises money for sudden infant death syndrome research, and First Candle, which aims to increases public awareness of SIDS.