Calvin Springer Hall, Jr., commonly known as Calvin S. Hall, was an American psychologist who studied in the fields of dream research and analysis. He began his systematic research on dreams in the 1940s, and from there he wrote many books, A Primer of Freudian Psychology and A Primer of Jungian Psychology being the best known, and developed a quantitative content analysis system for dreams. Hall's work on temperament and behavior genetics is now only a historical footnote, but was an aid to scientific studies and theories of today.