This research utilizes the geometric structure of the two-dimensional Interpersonal Circumplex (IPC), and adds the Five-Factor Model (FFM) dimension of conscientiousness to create a three-dimensional spherical model of personality; the interpersonal sphere (IPS). A sample of 250 participants was initially used to select items that conformed to the geometric locations of 26 different characteristics on the IPS. A separate sample of 251 participants confirmed the geometric structure of these characteristic measures using randomization tests. To demonstrate an application of this three-dimensional model, the IPS was employed as a geometric taxonomy to map various personality constructs. The combined sample of 501 participants was used to cartographically locate 164 scales from the NEO Personality Inventory, (NEO-PI-R), the 16 Personality Factor Questionnaire (16PF), the California Psychological Inventory (CPI), the Hogan Personality Inventory (HPI), the Temperament and Character Inventory (TCI), the Multidimensional Personality Questionnaire (MPQ), and the Jackson Personality Inventory (JPI-R) onto the IPS. The spherical conception of traits provided by the three-dimensional IPS is discussed as both an extension of the FFM and the two-dimensional IPC. Copyright © 2006 John Wiley & Sons, Ltd.