Theater rehearsals are (usually) confronted with the problem of having to transform a written text into an audio-visual, situated and temporal performance. Our contribution focuses on the emergence and stabilization of a gestural form as a solution for embodying a certain aesthetic concept which is derived from the script. This process involves instructions and negotiations, making the process of stabilization publicly and thus intersubjectively accessible. As scenes are repeatedly rehearsed, rehearsals are perspicuous settings for tracking interactional histories. Based on videotaped (...) professional theatre interactions in Germany, we focus on consecutive instances of rehearsing the same scene and trace the interactional history of a particular gesture. This gesture is used by the director to instruct the actors to play a particular aspect of a scene adopting a certain aesthetic concept. Stabilization requires the emergence of shared knowledge. We will show the practices by which shared knowledge is established over time during the rehearsal process and, in turn, how the accumulation of knowledge contributes to a change in the interactional practices themselves. Specifically, we show how a gesture emerges in the process of developing and embodying an aesthetic concept, and how this gesture eventually becomes a sign that refers to and evokes accumulated knowledge. At the same time, we show how this accumulated knowledge changes the instructional activities in the rehearsal process. Our study contributes to the overall understanding of knowledge accumulation in interaction in general and in theater rehearsals in particular. At the same time, it is devoted to the central importance of gestures in theater, which are both a means and a product of theatrical staging. (shrink)