DiSC is a behavior assessment tool based on the DISC theory of psychologist William Moulton Marston, which centers on four different behavioral traits: dominance, inducement, submission, and compliance. This theory was then developed into a behavioral assessment tool by industrial psychologist Walter Vernon Clarke.
It is important to understand that DiSC is not a personality assessment, but rather an assessment of behavior in given circumstances; for example, most people would say they do not behave the same at home and at work - but they are the same single personality.
There are many different versions of the questionnaire and profile. Because the versions of the assessment do vary, practitioners are cautioned to ask for evidence for the validity of a prospective version before using.
Marston was an accomplished man who was not only a lawyer and a psychologist; he also produced the first functional lie detector polygraph, authored self-help books and created the Wonder Woman comic. His major contribution to psychology came when he generated the DISC characteristics of emotions and behavior of normal people. Marston, after conducting research on human emotions, published his findings in his 1928 book called Emotions of Normal People in which he explained that people illustrate their emotions using four behavior types: Dominance (D), Inducement (I), Submission (S), and Compliance (C). Also, he argued that these behavioral types came from people’s sense of self and their interaction with the environment. He included two dimensions that influenced people’s emotional behavior. The first dimension is whether a person views his environment as favorable or unfavorable. The second dimension is whether a person perceives himself as having control or lack of control over his environment. His work was the foundation of the DISC assessment that has been used by more than 50 million people since it was first introduced in 1972.
 Although William Moulton Marston contributed to the creation of the DISC Assessment, he did not create it or even intend to use DISC as an assessment. In 1956, Walter Clarke, an industrial psychologist, was able to accidentally construct the DISC assessment using William Moulton Marston’s theory of the DISC model. He accomplished this by publishing the Activity Vector Analysis, a checklist of adjectives on which he asked people to indicate descriptions that were accurate about themselves. This assessment was intended for use in businesses needing assistance in choosing qualified employees.
About 10 years later, Walter Clarke Associates developed a new version of this instrument for John Cleaver. It was called Self Description. Instead of using a checklist, this test forced respondents to make a choice between two or more terms. Factor analysis of this assessment added to the support of a DISC-based instrument. Self Description was used by John Geier, Ph.D., to create the original Personal Profile System® (PPS) in the 1970s. Through hundreds of clinical interviews, he furthered the understanding of the 15 basic patterns discovered by Clarke.
Since then, a number of publishers have updated and/or generated their own versions of the DISC assessment. These have had varying degrees of validity and reliability; it has been questioned, however, whether DISC assessment in general has more than a degree of scientific validity as a psychometric instrument. However, in 1984 Dr. Jack Morrison's doctoral dissertation, "A Correlation Study of the Personal Profile System with the Sixteen Personality Factors Questionnaire" concluded that the DiSC has construct validity with significant correlations compared to the 16 PF strongly suggesting that it has scientific validity as a psychometric instrument. 
Some companies use the DISC assessment as a way to screen potential employees, with the thought that a certain personality type would be better or worse in certain jobs or positions. This is not what the DISC assessment was initially designed for. DISC is a tool to get to know oneself, others and behaviour in interpersonal situations better.
The best use of DISC is to learn more about yourself, others and how to deal in situations where interpersonal relationships are involved. Some more specific versions of the DISC assessment will help understand how one person would be likely to react in specific team, management or leadership situations, given her or his DISC style.
The assessment has been used to determine leadership. There are different leadership methods and styles that coincide with each personality type, which could help leaders be more effective. DISC has also been used to help determine a course of action when dealing with problems as a leadership team—that is, taking the various aspects of each type into account when solving problems or assigning jobs.
The DISC assessment tool, in its original version, based on the 24 or 28 four-box forced choice questionnaire, is used to identify 15 patterns:
- Objective Thinker
In the more recent versions of disc, the model is represented with a circle or circumplex, illustrating the four styles as four areas in the circle. This representation of the disc model links to the original, which was also represented in a circle. With colors and the right explanations, it is easier to view and understand the effort and adapting it takes for a particular style to reach common ground with another style. By doing so getting on the same wavelength between two people becomes easier.
- Myers-Briggs Type Indicator
- Herrmann Brain Dominance Instrument
- Keirsey Temperament Sorter
- Personality psychology
- Learning styles
- Hartman Personality Profile
- Marston, William M. (1928). Emotions of Normal People. K. Paul, Trench, Trubner & Co. ltd. p. 405.
- PeopleKeys, 2011
- Beamish, G. (2005). How chief executives learn and what behaviour factors distinguish them from other people. Industrial and Commercial Training, 37(3), 138 - 144.
- Sriram, Gayathri. "Communications: simple, easy, and stress-free!". Pure Visibility. Retrieved 10 July 2013.
- Duck, J. (2006). Making the connection: Improving virtual team performance through behavioral assessment profiling and behavioral cues. Developments in Business Simulation and Experiential Learning, 33, 358-9. Retrieved from http://sbaweb.wayne.edu/~absel/bkl/.\vol33\33cb.pdf
- IPB Partners (2014). Experts in developing people's behavioral skills. DiSC method, online assessments and DiSC certification. Retrieved from http://www.ipbpartners.eu/eng