Research in collaborative learning has supported the hypothesis that dialogue between peers and between peers and teachers facilitates learning by the peer participants in the dialogue. Examples of these dialogues show dozens of turns (individual utterances by participants) in a single learning session. In contrast, measurements of interaction from computer-supported collaborative learning environments show that on-line dialogue looks much different, with an average of approximately one posting or less per student per week. Measurements of learning in these environments do suggest learning is occurring, but presumably, not based on the same kind of dialogue described in research on face-to-face collaboration. Some possible explanations for how the learning is arising in CSCL environments are offered based on the Vicarious Learning Project (Lee, Dineen, McKendree, & Mayes, 1999; McKendree, Stenning, Mayes, Lee, & Cox, 1998). We believe that much of the learning in CSCL environments occurs from the observation of the dialogue, the reflection induced by the potential of submitting, and at least in the cases described, the interaction between the face-to-face and on-line environments.