An informal history of the interpersonal circumplex tradition.

Circular representations of human nature can be traced from ancient astrology to Leonardo Da Vinci to the modern interpersonal circumplex (IPC) tradition. which began with Harry Stack Sullivan. The Kaiser Foundation Psychology Research Group operationalized key concepts of Sullivan's and Timothy Leary (1957) provided extensions of Sullivanian theory that formed the conceptual basis for contemporary circumplex models The current generation of circumplex investigators is exceptionally well represented by the contributors to this special series. The IPC can serve as an integrative cognitive framework for making sense of diverse realms that are well outside its original focus of convenience. The visual and psychological appeal of this powerful model is briefly illustrated.