An expanded edition of Don Riso's revoluntionary interpretation of the Enneagram--the ancient psychological system used to understand the human personality. This expanded edition of Don Riso's classic for the first time uncovers the Core Dynamics, or Levels of Development, within each type. This skeletal system provides far more information about the inner tension and movements of the nine personalities than has previously been published. This increased specificity will allow therapists, social workers, personnel managers, students of the Enneagram, and general readers alike to use it with much greater precision as they unlock the secrets of self-understanding, and thus self-transformation.