Mueller met his future wife, Ann Cabell Standish, at a high school party when they were 17.[86] Standish attended Miss Porter's School in Farmington, Connecticut, and Sarah Lawrence College, before working as a special-education teacher for children with learning disabilities.[87] In September 1966, they married at St. Stephen's Episcopal Church in Sewickley, Pennsylvania.[88][89] They have two daughters and three grandchildren.[90] One of their daughters was born with spina bifida.[91]