John L. Holland

John Lewis Holland was an American psychologist and professor emeritus at Johns Hopkins University who created the influential Holland Codes theory of career choice. His model holds that people and work environments can be sorted into six types, Realistic, Investigative, Artistic, Social, Enterprising and Conventional, and that people flourish in careers matching their own type. He developed assessment tools built on the theory, including the Self-Directed Search in 1970, and the framework became foundational to career counseling research and practice.