Much of the work in the Learning Sciences and Computer-Supported Collaborated Learning communities have focused on understanding and designing for learning in collaborative spaces. This work utilizes methods such as Interaction Analysis and has attended to multiple dimensions and timescales of learning. It has redefined ideas about knowledge and competence and how they are acquired, thus providing important insights into the process of learning and the design of learning environments. However, we have not in the same way advanced our knowledge of teacher learning. Our understanding of the process and mechanism of teacher learning in in collaborative professional development (PD) environments is still quite thin. In this paper, we discuss how utilizing methods from Interaction Analysis, in particular, can offer insight into the process of teacher learning in these contexts. We illustrate how adopting a lens that shifts away from asking whether teachers are progressing toward a researcher-defined goal, toward one that asks how learning occurs in the moments of interaction, and the meaning it has for participants as they work to achieve PD goals, has the potential to shed new light on learning in teacher PD.