Don Richard Riso

Don Richard Riso (1946–2012) was an American teacher, researcher, and author who became one of the world's foremost authorities on the Enneagram of Personality. A graduate of Stanford University with a Master's degree in English and philosophy, Riso's encounter with the Enneagram began in 1974 while studying in Toronto as a Jesuit seminarian. Recognizing the system's profound potential, he dedicated the following decade to rigorous scholarly research — spending years in the stacks of Harvard's library to develop the first detailed, psychologically grounded descriptions of the nine personality types. His landmark debut, Personality Types: Using the Enneagram for Self-Discovery (1987), introduced the system to a mainstream audience and established him as a pioneering voice in personality psychology.

Riso's most enduring contribution was his collaborative partnership with Russ Hudson, whom he began working with in 1991. Together they developed the Riso-Hudson Enneagram Type Indicator (RHETI), a scientifically validated 144-item assessment that remains one of the most widely used personality tests of its kind. In 1995 they co-founded the Enneagram Institute in New York, building an international educational network spanning more than fifteen countries. Their co-authored works — including The Wisdom of the Enneagram (1999) and Discovering Your Personality Type (2003) — brought together deep psychological insight with practical tools for self-awareness and personal growth. Riso also introduced the concept of "nine levels of development" within each type, a framework that illuminated the full spectrum of human behavior from health to dysfunction.

Nightingale-Conant's catalog features Don Richard Riso's teachings as part of its curated library of personal development programs, where his Enneagram work sits alongside other transformative frameworks for understanding human motivation and character. His books and programs continue to guide individuals seeking self-knowledge and more compassionate relationships with themselves and others. Don Richard Riso passed away on August 30, 2012, leaving behind a body of work that fundamentally reshaped how millions understand personality and human potential.