The structure of the discipline of Communication is examined using the frequency of joint memberships in the International Communication Association's divisions and interest groups. The results suggest that the structure is more complex than previously suggested by bibliometric research. There are at least two dimensions that differentiate the divisions/interest groups. As reported in the bibliometric literature, one is a dimension that separates the mass media and the interpersonally oriented divisions. The second differentiates the humanistic from the scientific. One method found a third dimension: theoretical to applied. Cluster analysis based on the actual number of joint memberships found three clusters: humanistic, mediated, and interpersonal. A cluster analysis that controlled for the size of the divisions/interest groups found only two: humanistic and scientific. Blockmodeling of the joint memberships identified four: humanistic, mediated, interpersonal, and information technology.