[2] Kelly proposed that individuals can be psychologically evaluated according to similarity–dissimilarity poles, which he called personal constructs (schemas, or ways of seeing the world).
[3] From the theory, Kelly derived a psychotherapy approach, as well as a technique called the repertory grid interview, that helped his patients to analyze their own personal constructs with minimal intervention or interpretation by the therapist.
[5] The UK Council for Psychotherapy, a regulatory body, classifies PCP therapy within the experiential subset of the constructivist school.
A main tenet of PCP theory is that a person's unique psychological processes are channeled by the way they anticipate events.
"Every man is, in his own particular way, a scientist", said Kelly: people are constantly building up and refining theories and models about how the world works so that they can anticipate future events.
Kelly explicitly stated that each individual's task in understanding their personal psychology is to put in order the facts of their own experience.
If the results of their actions are in line with what the knowledge predicted, then they have done a good job of finding the order in their personal experience.
The repertory grid serves as part of various assessment methods to elicit and examine an individual's repertoire of personal constructs.
During the last 30 years, it has gradually gained adherents in the US, Canada, the UK, Germany, Australia, Ireland, Italy and Spain.
The repertory grid is often used in the qualitative phase of market research, to identify the ways in which consumers construe products and services.