The Enneagram: A systematic review of the literature and directions for future research.

The Enneagram is a typology that many clients use to understand their personality and interpersonal patterns, despite some concerns about its validity. Thus, the purpose of this review is to provide a comprehensive and clinician-friendly review of the extant empirical work on the Enneagram. After reviewing 104 independent samples, we found mixed evidence of reliability and validity. In terms of strengths, some factor analytic work has shown partial alignment with prior theorizing, and subscales show theory-consistent relationships with other constructs such as the Big 5. Also, several studies found the Enneagram was helpful for personal/spiritual growth. However, factor analytic work has typically found fewer than nine factors, and no work has used clustering techniques to derive the nine types. Also, there is little research supporting secondary aspects of Enneagram theory, such as wings and intertype movement. We conclude by highlighting directions for future research and implications for clinical practice.