The DiSC personality assessment model was developed in the 1920s by William Moulton Marston based on concepts of normal behavior. Walter Clark created the first assessment using Marston's work in 1942 called Activity Vector Analysis. In the 1970s, John Geier developed the Personal Profile System and founded Performax, the first publisher of DiSC assessments. Performax became Inscape Publishing and conducted research to improve reliability. Inscape launched an online version in 2003 and was later purchased by John Wiley & Sons in 2012, who continues research on the Everything DiSC assessment.