The purpose of the study, in order to improve the courses presented in online environments based on Community of Inquiry, is to investigate relations among the Community of Inquiry' presences (teaching, social and cognitive), learners' characteristics (e.g. gender, age, occupational status, and the type of registered program), "e-readiness and expectations", and satisfaction by using the structural equation model. The study group consisted of 714 students enrolled in distance education programs. Three data collection tools were used to collect data. The findings revealed that "the presence of the students was at a moderate level, teaching and social presence had a significant positive effect of on cognitive presence, the level of presence did not vary based on the variables of demographic and discipline, the e-presence and expectation levels had a low impact on presence levels, and the level of presence had a significantly high impact on satisfaction." The findings also indicated that the online courses examined in this study were found to be sufficient by students in forming a community of inquiry. However, it also revealed that certain aspects of the courses should be improved. Therefore, it could be concluded that there is a need for more social, more active and engaging learning activities that enable students to think critically in an online environment.