High scores on the Cook-Medley hostility scale (Ho) have been associated with enhanced risk for physical disorders, psychological dysfunction, and problems in interpersonal relationships. These outcomes appear to be produced by certain anger-related personality attributes reflected in Ho scores. There have been several efforts to describe those attributes, but no empirical attempts to determine which description corresponds most closely to the structure of relationships among Ho items. This study employed confirmatory factor analysis to evaluate nine models variously specifying that from one to five distinct characteristics are reflected in Ho scores. Five models were based on previous research, and four were derived from exploratory factor analysis. Results for all nine models indicated an equivalently poor degree of fit with the data. Thus, although the Ho shows validity as a predictor of medical, psychological, and interpersonal outcomes, and appears to index attributes that may reasonably be described as “hostile,” it may lack the coherent internal structure required for measuring distinctive psychological traits.