Theoretical Origins
The typology was developed and copyrighted by John Holland to organize the voluminous data about people in different jobs and the data about different work environments, to suggest how people make vocational choices and careers and to explain how job satisfaction and vocational achievement occur.

Principal Elements
Most people can be categorized as one of six types: 
Realistic, Investigative, Artistic, Social, Enterprising and Conventional. This is a theoreti-cal or ideal type, i.e., a model against which we can mea-sure the real person.

The six scales of the SDS estimate a person’s resem-blance to each of the personality types. By indicating the 3 types a person resembles most, the 3-letter Summary Code allows for the complexity of personality and reduces some of the problems inherent in categorizing a person as a single type.

Cultural and personal forces - parents, social class, cul-ture, and the physical environment - shape people in dif-ferent ways. Out of these experiences, a person learns to prefer some activities over others. Later, the pre-ferred activities become strong interests, which tend to lead to a special group of competencies. Finally, a per-son’s interests and competencies create a particular per-sonal disposition that leads to thinking, perceiving, and acting in special ways. This developmental sequence does not end in young adulthood but continues to evolve, depending on the different environments people encounter in their lifetimes.

There are six kinds of environments: 
Realistic, Investigative, Artistic, Social, Enterprising and Conven-tional. Each environment is dominated by a given type of personality and is typified by physical settings posing special problems. For example, a social environment, dominated by social types, often requires interaction with people in helping or teaching activities.

People tend to surround themselves with others like themselves who share their interests, competencies, and outlook on the world. Thus, where people congregate, they create an environment that reflects their personal-ity. People search for environments that will let them exercise their skills and abilities, express their attitudes and values, and take on agreeable problems and roles.

The SDS assesses the outcomes of a person’s life history and assigns it a three-letter code. We can use a person’s Summary Code to locate occupations - actually, work environments - that will result in satisfaction. The typology can be used to examine the relation of a person’s type to one or more occupational alternatives; thus, an SIA person is expected to find sat-isfaction in an SIA job, because the SIA person’s charac-teristic activities, competencies, perceptions, values, and traits resemble those of typical SIA workers, and the job provides opportunities for the expression of these per-sonal characteristics.

Holland Types
Research has provided a wealth of information about the six basic types. The descriptions below are brief portraits of each of the types.

Realistic (R) individuals prefer realistic careers such as mechanical engineer and building inspector. The R type usually has mechanical and athletic abilities, enjoys working outdoors, and likes to work with tools and machines. The R type generally prefers to work with things rather than people. People usually describe the R type as being: conforming, frank, genuine, humble, modest, practical, natural, persistent, and thrifty.

Investigative (I) individuals prefer investigative careers such as orthodontist, economist, and management analyst. The I type usually has mathematical and scientific abilities, enjoys working alone, enjoys research, and likes to solve problems. The I type generally favors working with ideas rather than with people or things. People describe the I type as being: analytical, curious, methodical, rational, cautious, independent, precise, reserved, complex, intellectual, and modest.

Artistic (A) individuals prefer artistic careers such as architect, copy writer, stage director and interior decorator. The Atype usually has artistic skills, enjoys creating original work, and has a good imagination. The A type usually enjoys working with ideas rather than things. People describe the A type as being: open, imaginative, original, intuitive, emotional, independent, idealistic, and unconventional.

Social (S) individuals prefer social careers such as teacher, clinical psychologist and personnel manager. The S type usually has social skills, is interested in human relationships, and likes to help others with problems. The S type likes to work with people rather than with things. People describe the S type as being: helpful, responsible, warm, cooperative, idealistic, sociable, tactful, friendly, kind, sympathetic, generous, patient, and understanding.

Enterprising (E) individuals prefer enterprising careers such as public relations representative, financial planner, sales representative, stockbroker, and attorney. The E type usually has leadership and speaking abilities, is interested in economics and politics, and likes to be influential. The E type likes to work with people and ideas rather than things. People describe the E type as being: adventurous, energetic, optimistic, agreeable, extroverted, popular, sociable, self-confident, and ambitious.

Conventional (C) individuals prefer conventional careers such as accountant and budget analyst. The C type has clerical and arithmetic abilities, prefers working indoors, and likes to organize things. The C type enjoys working with words and numbers. People describe the C type as being: conforming, practical, careful, obedient, thrifty, efficient, orderly, conscientious, and persistent.

Very few people are “pure” types, in the sense that they have the characteristics of only one of the types. It is important, therefore, to recognize that most people have a combination of characteristics that may reflect two or more types. Your Holland code is shorthand for describing the types you resemble the most.