Popham retired from the Navy and NASA in 1969 and entered private business. He formed his own consulting company and served on the boards of several corporations, as well as the Board of Trustees for his alma mater, the University of Washington.
Popham is the author of several books, including:
- "Space Master: The Personal Odyssey of an Astronaut and CEO" (1989)
- "The Astronaut's Survival Guide: Seven Steps for Leading Your Team Through Crisis" (2006)
- "Leading from Above: How Top Leaders Create and Sustain Organizational Success" (2014)
- "The Man Who Fell to Earth: A Novel of Space, War, and the American Dream" (2015)