As higher education institutions enter the intense competition of the rapidly growing global marketplace of online education, the leaders within these institutions are challenged to identify factors critical for developing and for maintaining effective online courses. Computer mediated communication systems are considered one of the critical to the successful online courses. Using the Community of Inquiry Framework, this study, in two parts, examined the use of CMC systems. Results of the causal comparative design suggested no significant difference in cognitive presence, teacher presence, and perceived learning between online students who used only asynchronous CMC systems and those who used a combination of both asynchronous and synchronous CMC systems; however, the study did provide evidence that online students who used a combination of CMC systems had statistically significantly higher levels of social presence than the students who used only asynchronous CMC systems. Results of the true experimental design suggested no significant difference in social presence, cognitive presence, teacher presence, and perceived learning between the two groups of online students.