This study investigates how inservice teachers constructed new knowledge, the extent of knowledge construction achieved, and how instructors participated in and facilitated the online discussion to affect knowledge construction. One finding is that most inservice teachers seemed to favor discussion activities at the stage of knowledge confirmation rather than knowledge construction. Another finding is that some facilitation approaches used by the instructors when serving as both facilitator and co-participant were particularly helpful for enhancing knowledge construction. However, neither student-perceived learning nor satisfaction with instructor roles and facilitative strategies significantly differ between the two classes involved. (Contains 4 tables.)