In 1976, he established the H.A. and Mary K. Chapman Charitable Trust, a perpetual charitable private foundation that was fully funded with a bequest from his estate when he died in 1979.
Mary K. Chapman was born in Oklahoma in 1920. She graduated from the University of Tulsa and worked as a nurse before her marriage to Allen Chapman in 1960.
After the death of her husband in 1979, Mary Chapman maintained her own personal charitable giving program. Before her death in 2002, she established The Mary K. Chapman Foundation, a charitable trust founded to perpetuate her own charitable giving program. This foundation was fully funded with a bequest from her estate in 2005.