The purpose of this study was to specify the major parameters of inference in the reasoning behaviors of listeners in their acceptance of conclusions of arguments in the larger process of decision-making. From the 463 undergraduate speech subjects used in the study, 60 were chosen to play the role of "speakers" and 57 were chosen to play "listeners." Both groups were asked to evaluate 46 arguments on "The War in Vietnam" on five seven-point scales of effectiveness and logicalness. In another test of 34 different "speakers" and 36 "listeners," 20 content, attitudinal, and personality components and correlates of inference were investigated for 15 arguments varying in perceived effectiveness. For most of the hypotheses, a multiple regression program was used on the IBM 7044 computer. Findings indicated that subjects did not perceive theoretically more logical arguments as more "logical" or more "effective." Some of the conclusions reached were that the theoretical development of an argument tends to be unrelated to the actual reasoning behaviors; and that attitudes about content of arguments, structure of arguments, and certain attitude variables are primary components of the psychological acceptance of conclusions. (Author/DD)