This article considers four alternative types of definitions of interpersonal communication, each identifying an essential element of the phenomenon, named here (a) level, (b) quality, (c) basis for predictions, and (d) self-concept involvement. The definitions are described, an underlying similarity and relationship are examined, and a new definition of interpersonal communication is offered, accounting for the four essential elements. The implications of this definition to pedagogy as well as to theory and research are discussed