There is much literature addressing challenges face-to-face freshman composition instructors encounter in developing college courses that foster critical thinking skills crucial to developing written argument. Composition instructors may face challenges in teaching students that writing is a means of making meaning, there are many different methods of thinking and writing, and intellectual growth occurs when students are encouraged to use higher levels of thinking that push them beyond their normal thinking yet do not push them beyond their present abilities (Berlin, 1987; Berthoff, 1984; Lindemann, 1982). There is a gap in the literature on freshman composition, however, regarding students' using critical thinking skills to develop an argument during online composition courses. Because of this gap in the literature, composition instructors may need training and practice with feedback to create opportunities for freshman composition students to think critically and to develop high-quality arguments online (Palloff & Pratt, 2007). Researchers in online education have documented a relationship between critical thinking and social presence (i.e., online participants' perceptions of one another as real individuals in a shared space) (Tu & McIsaac, 2002). More recent researchers characterize social presence as an action, and they have suggested that the use of social presence cues may increase the incidence of critical thinking in the online course environment (Rourke, Anderson, Garrison, & Archer, 1999; Wise, Chang, Duffy, & Del Valle, 2004). The purpose of this study is to investigate whether online instructors' use of social presence cues affects students' demonstration of signs of critical thinking and argument development across multiple online freshman composition classes. In this study I found that the situational treatment instructors used more social presence cues in the posttraining segment of the study than they did in the pretraining. The discussion board postings and the essays were scored based on the Guide to Rating Critical and Integrative Thinking (GRCIT). In both the cognitive and situational treatments, the essay achievement scores increased after the training. An unexpected finding was that discussion board achievement scores decreased after training for all four participating instructors. After testing the hypotheses, I found that the incidence of social presence cues is not a predictor of students' achievement scores. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]