This study investigated the effect of time on the development of a community of inquiry by examining an online course offered over two different time periods. The study was guided by the Community of Inquiry (CoI) framework (Garrison, Anderson, & Archer, "The Internet and Higher Education" 2000; 2(2-3): 87-105). The focus was on a graduate level education course, the topic of which was blended learning. The course was given by the same instructor in a 13-week fall semester and a 6-week spring term. Transcript analysis of weekly online discussions and the CoI Survey were used to explore the differences between the short-term and long-term versions of this course in terms of each measure of CoI presence (social, teaching and cognitive presence). The findings showed differences between the short-term and long-term versions of this course in terms of the development of each presence and students' perceptions. (Contains 3 figures and 5 tables.)