The Enneagram of Personality, or simply the Enneagram, is a model of the human psyche which is principally understood and taught as a typology of nine interconnected personality types. 
 Although the origins and history of ideas associated with the Enneagram of Personality are disputed, contemporary approaches are principally derived from the teachings of the Bolivian psycho-spiritual teacher Oscar Ichazo from the 1950s and the Chilean psychiatrist Claudio Naranjo from the 1970s. Naranjo's theories were also influenced by earlier teachings about personality by George Gurdjieff and the Fourth Way tradition in the first half of the 20th century.
 As a typology, the Enneagram defines nine personality types (sometimes called "enneatypes"), which are represented by the points of a geometric figure called an enneagram, which indicate some of the principal connections between the types. There have been different schools of thought among Enneagram teachers and their understandings are not always in agreement.
 The Enneagram of Personality is promoted in both business management and spirituality contexts through seminars, conferences, books, magazines, and DVDs. In business contexts, it is often promoted as a means to gain insights into workplace interpersonal dynamics; in spirituality it is commonly presented as a path to states of enlightenment and essence. Proponents in both contexts say it has aided in self-awareness, self-understanding, and self-development. 
 There has been limited formal psychometric analysis of the Enneagram, and the peer-reviewed research that has been done is not accepted within the relevant academic communities. Though the Enneagram integrates some concepts that parallel other theories of personality, it has been dismissed by personality assessment experts as pseudoscience.
 The origins and historical development of the Enneagram of Personality are matters of dispute. Similar ideas to the Enneagram of Personality are found in the work of Evagrius Ponticus, a Christian mystic who lived in 4th-century Alexandria in Egypt. Evagrius identified eight logismoi ("deadly thoughts") plus an overarching thought he called "love of self". Evagrius wrote, "The first thought of all is that of love of self (philautia); after this, [come] the eight." In addition to identifying eight deadly thoughts, Evagrius also identified eight "remedies" to these thoughts.
 G. I. Gurdjieff (died 1949) is credited with first using the word enneagram and is the only known source for the geometric figure. He did not develop the nine personality types associated with the Enneagram of Personality. Instead, Gurdjieff used the enneagram figure for various other purposes, including sacred dances known as the Gurdjieff movements.
 Oscar Ichazo (1931–2020) is credited as the principal source of the contemporary Enneagram of Personality which is largely derived from parts of Ichazo's teachings, such as those on ego-fixations, holy ideas, passions, and virtues. The Bolivian-born Ichazo began teaching programs of self-development in the 1950s. His teaching, which he called "Protoanalysis", uses the enneagram figure among several other symbols and ideas. Ichazo founded the Arica Institute - which was originally based in Chile before moving to the United States - and coined the term "Enneagram of Personality" (which he originally called the "Enneagon of Personality").
 Claudio Naranjo (1932–2019) learned the Enneagram of Personality from Ichazo and then developed and taught his own understanding of the Enneagram in the United States, principally at the Esalen Institute and to his students in Berkeley, California. Two of his students were Jesuit priests who later adapted the Enneagram for use in Christian spirituality within programs at Loyola University in Chicago. Ichazo originally strongly objected to the Enneagram teachings of Naranjo and other teachers due to what he considered their misinterpretations and misuses of the Enneagram. 
 Naranjo's teachings became increasingly popular in the United States and elsewhere from the 1970s. Numerous other authors also published books on the Enneagram of Personality in the 1980s and 1990s. Those authors included Don Richard Riso (1987), Helen Palmer [Wikidata] (1988), Eli Jaxon-Bear (1989), Elizabeth Wagele (1994), and Richard Rohr (1995). In 1994, the First International Enneagram Conference, attended by around 1,400 participants, was held at Stanford University and co-sponsored by the university's psychiatry department where psychiatrist, Enneagram author, and conference co-director David Daniels [Wikidata] was teaching.
 Analysis of Google search results over 16 years shows an increase in searches for the word "enneagram" from 2017. Additionally, social media accounts and podcasts about the Enneagram have increased, indicating a growing popularity among millennials. It has been suggested that the rise in popularity of the Enneagram parallels a renewed interest in astrology.
 The enneagram figure is composed of three parts; a circle, an inner triangle (connecting 3-6-9), and an irregular hexagonal "periodic figure" (connecting 1-4-2-8-5-7). According to esoteric spiritual traditions, the circle symbolizes unity, the inner triangle symbolizes the "law of three" and the hexagram represents the "law of seven" (because 1-4-2-8-5-7-1 is the repeating decimal created by dividing one by seven in base 10 arithmetic). These three elements constitute the usual enneagram figure.
 The table below offers an outline of the principal characteristics of the nine types along with their basic relationships. This table expands upon Oscar Ichazo's ego fixations, holy ideas, passions, and virtues primarily using material from Understanding the Enneagram: The Practical Guide to Personality Types (revised edition) by Don Richard Riso and Russ Hudson as well as Charles Tart's Transpersonal Psychologies. Other theorists may disagree on some aspects. The types are normally referred to by their numbers, but sometimes their "characteristic roles" (which refers to distinctive archetypal characteristics) are used instead. Various labels for each type are commonly used by different authors and teachers. The "stress" and "security" points (sometimes referred to as the "disintegration" and "integration" points) are the types connected by the lines of the enneagram figure and are believed to influence a person in an adverse or relaxed circumstance. According to this hypothesis, someone with a primary One type, for example, may begin to think, feel, and act more like someone with a Four type when stressed or a Seven type when relaxed.
 The nine Enneagram personality type patterns are grouped into various triads of three types in which each of the types have multiple common personality issues. The most well-known of these triad groupings is also associated with the three "centers of intelligence" as taught by G. I. Gurdjieff. These three centers are traditionally known as the intellectual, emotional, and instinctual centers. Although each person is understood to always have all three centers active in their personality structure, certain personality issues are more associated with one of the centers depending on a person's dominant type pattern. In Enneagram of Personality teachings each of these centers has a particular association with one of the triads of personality types as follows:     
 Most, but not all, Enneagram of Personality enthusiasts teach that a person's basic type is modified, at least to some extent, by the personality dynamics of the two adjacent types as indicated on the enneagram figure. These two types are called "wings". A person with the Three personality type, for example, is understood to have points Two and Four as their wing types. The circle of the enneagram figure may indicate that the types or points exist on a spectrum rather than as distinct types or points unrelated to those adjacent to them. A person may be understood, therefore, to have a core type and one or two wing types which influence but do not change the core type. Empirical research into the wing concept by Anthony Edwards did not support the hypothesis. Related to, but not the same, as the wing concept is Ichazo's viewpoint involving the active, attractive, and function forces. According to him, the type is made from a starting point, referred to as the active force. In turn, the type is also led with an attractive force. This ends with the "function", where the result is the formation of a type in between the two. Naranjo said about the wings that a person "can easily see" their primary type as being between its adjacent wings.
 For some Enneagram theorists the lines connecting the points add further meaning to the information provided by the descriptions of the types. Sometimes called the "security" and "stress" points, or points of "integration" and "disintegration", some theorists believe these connected points also contribute to a person's overall personality. From this viewpoint, therefore, at least four other points affect a person's overall personality; the two points connected by the lines to the core type and the two wing points. The earlier teachings about the connecting lines are now rejected or modified by Enneagram teachers, including Claudio Naranjo who developed them.
 Each of the personality types is understood as having three "instinctual subtypes". These subtypes are believed to be formed according to which one of three instinctual energies of a person is dominantly developed and expressed. The instinctual energies are called "self-preservation", "sexual" (also called "intimacy" or "one-to-one"), and "social". On the instinctual level, people may internally stress and externally express the need to protect themselves (self-preservation), to connect with important others or partners (sexual), or to get along or succeed in groups (social). From this perspective, there are twenty-seven distinct personality patterns, because people of each of the nine types also express themselves as one of the three subtypes. An alternative approach to the subtypes looks at them as three domains or clusters of instincts that result in increased probability of survival (the "preserving" domain), increased skill in navigating the social environment (the "navigating" domain), and increased likelihood of reproductive success (the "transmitting" domain). From this understanding the subtypes reflect individual differences in the presence of these three separate clusters of instincts.
 It is believed that people function in all three forms of instinctual energies, but one instinct will be more well-developed and dominant.
 Enneagram type indicator tests have been developed by prominent teachers, such as Don Richard Riso and Russ Hudson who developed the Riso–Hudson Enneagram Type Indicator (RHETI) in 1993. Their research focused on constructing it as a personality measurement instrument. The RHETI has heuristic value but minimal scientific research conducted. 
 The Stanford Enneagram Discovery Inventory was developed by psychiatry professor David Daniels at Stanford University and was later renamed the Essential Enneagram Test. This assessment was employed to conduct various research studies, including on the personalities of identical twins.
 A 2002 review of validation studies of various Enneagram tests found guarded support for their reliability and validity.
 While Enneagram teachings have attained a degree of popularity, they have been categorized by many professionals as a pseudoscience due to their subjectivity and inability to be tested scientifically, and described as "an assessment method of no demonstrated reliability or validity". In 2011, the scientific skeptic Robert Todd Carroll included the Enneagram in a list of pseudoscientific theories that "can't be tested because they are so vague and malleable that anything relevant can be shoehorned to fit the theory".
 A 2020 review of Enneagram empirical work found mixed results for the model's reliability and validity. The study noted that the ipsative version of the Riso-Hudson Enneagram Type Indicator (scores on one dimension decrease scores on another dimension) had troubles with validity, whereas the non-ipsative version of the test has been found to have better internal consistency and test-retest reliability. It was found that 87% of individuals were able to accurately predict their Enneagram type (before taking the test) by being read descriptions of each type.
 In a Delphi poll of 101 doctoral-level members of psychological organizations such as the American Psychological Association, the Enneagram was among five psychological treatments and tests which were rated by at least 25% of them as being discredited for personality assessment. Experts familiar with the Enneagram rated it with a mean score of 4.14 (3.37 in the first round of the study) which is approximately an equivalent to the option "probably discredited" (3 = possibly discredited, 4 = probably discredited, 5 = certainly discredited).
 The Enneagram has also received criticism from religious perspectives. In 2000, the United States Conference of Catholic Bishops' Committee on Doctrine produced a draft report on the origins of the Enneagram to aid bishops in their evaluation of its use in their dioceses. The report identified aspects of the intersection between the Enneagram and Roman Catholicism which, in their opinion, warranted scrutiny with potential areas of concern, stating, "While the enneagram system shares little with traditional Christian doctrine or spirituality, it also shares little with the methods and criteria of modern science ... The burden of proof is on proponents of the enneagram to furnish scientific evidence for their claims." Partly in response to Jesuits and members of other religious orders teaching a Christian understanding of the Enneagram of Personality, a 2003 Vatican document called Jesus Christ, the Bearer of the Water of Life. A Christian Reflection on the 'New Age' said that the Enneagram "when used as a means of spiritual growth introduces an ambiguity in the doctrine and the life of the Christian faith".