Asynchronous conferencing is emerging as a tool that can create opportunities for collaboration and support the inquiry process. This paper describes one such tool (ACT) designed within a specific pedagogical framework. The overall goal of ACT is to make cognitive processes visible and encourage reflection in students as they engage in critical thinking activities. This study examines the use of ACT within a graduate-level seminar and an upper-level undergraduate sociology course. We report on the tasks assigned to the students, levels of participa-tion, and ways in which special features of ACT helped support specific pedagogical goals in the two courses. Using ACT helped the instructors meet their goals; in both cases, they reported that students displayed better crit-ical thinking skills than in past semesters. Most interesting was the use of labels; textual, color-coded tags associ-ated with each message. Sets of labels defined by the instructors successfully facilitated specific student activities and promoted reflection.