The objective of this research was to compare the quality and quantity of teacher and student interaction in an on-line versus face-to-face learning environment. A Master's level course on nursing theories was taught by the same professor by both methods. Transcripts of the face-to-face class and on-line postings were analyzed to identify professor behaviors and also to rate the levels of student responses using the Gunawardena, Lowe and Anderson (1997) Analysis Model for Social Construction of Knowledge. Categories of teacher behaviors were identified and frequencies calculated in each course. While numbers of interventions were different, the professor showed similar facilitation behaviors in both environments. Student participations were counted and rated using the five major phases of the model. While most student interactions reflected the lower levels of the model, some students in each delivery context demonstrated higher levels of knowledge construction. Students experiencing each delivery method were successful in the course and mastered complex, abstract concepts. (Contains 2 tables.)