An important characteristic of expert teaching is the ability to adapt instruction to meet learners' needs. One way this type of ownership of instruction happens is through teachers interactively constructing knowledge about pedagogical content with others. In this article, the authors looked at how a group of thirteen participants enrolled in an online literacy Master's program engaged in video-mediated discussions which resulted in varying degrees of instructional ownership. The participants were students in a class on word study, a differentiated approach to supporting students' phonics, spelling, and vocabulary development. Analyzing over 70 hours of video recordings, we traced teachers' discursive construction of ownership over word study for a semester, orienting to their sense-making processes as the construction of a personal stance toward word study through interaction with one another. Detailed analysis is used to examine patterned variability in ownership stances expressed by participants; these patterns are implicated in teachers' capacity to develop adaptive expertise through peer support.