The first purpose of the present study was to characterize progressive and metacognitive dialogue in knowledge-building classrooms. The second purpose was to examine the association between the quality of classroom dialogue and students' learning outcomes, including domain knowledge and conception of collaboration. One hundred thirty college students and their teacher participated in this study. A total of 73 lessons were video-recorded. Qualitative analysis of ­classroom dialogue identified dialogic moves into three categories--articulation and elaboration, building-on and connection, and reflection and coordination. The findings provide a rich illustration of how students engage in metacognitive and progressive dialogue. Quantitative analysis indicated that student engagement in classroom dialogue was positively associated with their domain knowledge and conception of collaboration. The results revealed that considering student involvement in classroom dialogue is essential for understanding how knowledge building occurs in classroom contexts and how collective knowledge and conception of collaboration are developed through classroom dialogue.