Forty years ago, the Kaiser Research group pioneered an approach to interpersonal assessment based on a structural model of personality, the interpersonal circle. With renewed interest in circular models, issues about the measurement, analysis, and application of these kinds of individual data reemerge. This article is an introduction to and revision of the basic principles of circular profile analysis. Using the recent circumplex of interpersonal problems, we define the model and its data, explain the structural summary, and discuss the descriptive and possible clinical significance of profile indices. Future researchers should seek to expand understanding of how circular profile variables relate to clinical assessment and treatment, and also apply the analytic methods to test key aspects of interpersonal theory.