In this study, we assessed the communication structure in an educational online learning environment using social network analysis (SNA). The communication structure was examined with respect to time, and instructors' participation. The course was implemented using ELGG, a network learning environment, blended with face-to-face sessions over a 14-week period. Data were collected from 114 undergraduate students who were enrolled in Instructional Technology and Material Design course. The program functions on the basis of a matrix; in this case a square matrix with rows and columns being the students' ID numbers. Density and centrality measures were visualized and interpreted. In terms of the density of the groups, it was found that the lowest density occurred during the first week. The highest density, on the other hand, occurred during the week when the instructor participated, in all the groups except for the third and sixth groups. The students placed in the center and those on the edges of the network differed on the basis of time as well as the instructor's participation. Other online learning environments could be assessed in a similar fashion using SNA in order to understand levels of participation and changes in interaction over time.