A study tested those theories upon which instruction and curriculum in speech and public communication are based. The study investigated the relationship of mode of delivery on ratings of individual speech characteristics as well as the relationship of these perceptions of effectiveness in a public communication setting. Twenty-four videotapes of undergraduate college students delivering 5-minute speeches in an introductory speech class were selected for the study, half of which used the extemporaneous mode, and the other half, the manuscript mode. Twenty-four student evaluators (communication majors chosen from an elective course in communication theory) evaluated the 24 speeches. Results indicated that there was a significant relationship between the mode of delivery chosen by the speaker and the criteria on which the speech was evaluated. Ratings of these factors more frequently fell into the superior category when the mode of delivery was extemporaneous. Results also showed that the characteristics evaluated do not contribute equally to perceptions and related ratings of effectiveness. On the basis of simple bivariate correlations, delivery and speaker credibility would appear to bear the strongest relationship to perceived effectiveness. The more refined regression analysis, moreover, indicated that the prediction equation that can be generated from the data would weight delivery most heavily. (Eight tables of data are included; 16 notes are attached.) (PRA)