Don Richard Riso

Don Richard Riso (17 January 1946 – August 30, 2012) was an American teacher of the Enneagram of Personality who wrote and co-wrote a number of books on the subject. Riso grew up in New Orleans, Louisiana. He studied English and philosophy and received an M.A. from Stanford University. Around 1962, he joined the Society of Jesus (Jesuits) of the New Orleans Province but later left the order without being ordained. In the early 1970s, some members of the Jesuit order came in contact with Enneagram of Personality materials as it was beginning to be taught in Jesuit and other Roman Catholic institutions in North America. 

In 1974, as a Jesuit seminarian in Toronto, Canada, Riso first learned of the Jesuit teachings on the Enneagram from Jesuit priest Tad Dunne. Riso said the Jesuit teachings on the Enneagram "consisted of nine one-page impressionistic sketches of the personality types" and fascinated him. In the following year, 1975, he left the order and began developing the brief type sketches into more detailed descriptions.

Riso developed a number of original ideas regarding understanding the Enneagram, such as nine "levels of development" from "liberated" or "healthy" to "pathologically unhealthy." Riso spent 10 years in the Harvard library almost daily, from 10 am to 5 pm, developing these ideas.

In 1987, Riso published his 12 years of Enneagram thinking in his first book, Personality Types: Using the Enneagram for Self-Discovery. This work showed the influence of Carl Gustav Jung and also of Karen Horney. Three years later, he published Understanding the Enneagram.

In 1991, Russ Hudson joined Riso, originally to create a questionnaire for indicating people's Enneagram types. The result was the Riso–Hudson Enneagram Type Indicator (RHETI). Several versions have since been developed, the present complete version consisting of 144 pairs of forced-choice statements.

In 1995, Riso and Hudson founded the Enneagram Institute in New York City. The institute has since moved to Stone Ridge, New York, where it offers workshops and training as well as publishing materials pertaining to the Enneagram. The Enneagram Institute Network represents it in more than 15 countries. Hudson participated in revising the book Personality Types for the second edition, which came out in 1996. Riso considered himself to be Enneagram type Four. Riso died on August 30, 2012, at 2:07 am, from metastasized pancreatic cancer.