This four-year study of a communication-intensive university learning community (Agronomy 356: Soil, Water, and Fertilizer Management and English 309: Report and Proposal Writing) investigated how instructor collaboration influenced written cross-disciplinary teacher feedback. While some rule-bound knowledge was not shared across disciplinary boundaries, co-assigning and co-assessing a rhetorically situated, argument-based writing assignment enabled my four instructor-participants to collaborate meaningfully and to integrate both agronomic and communicative knowledge into their feedback. Using activity theory, I analyzed how collaboration affected instructors' feedback patterns, roles, and styles, as well as the ways disciplinary knowledge of agronomy and rhetoric was communicated through feedback. My mixed-methodology design used interviews and observations along with statistical analyses of 2,660 feedback items.;Patterns. The instructors' participation in one another's courses during years one through three contributed to the statistically significant increase in argument feedback during this period (55%, 62%, 73%), while the decrease during year four (53%) was prompted by changes in teaching personnel, modifications in an instructor's feedback style, and a decline in veteran instructors' participation in one another's courses. These findings suggest that cross-disciplinary collaboration is important for integrating agronomy and rhetoric in teacher feedback.;Roles. All instructors perceived their feedback motives/objects to be both academic- and workplace-based, while three instructors articulated using rhetorical situation as a feedback tool. Both these perceived motives and tool-uses were influenced by instructors' participation in various academic and workplace activity systems. These findings indicate not only that feedback roles were influenced by a variety of instructor experiences but also that rhetorical situation was presented to students as fixed while instructors used it as a malleable feedback tool.;Style/disciplinary knowledge. Although only one instructor altered his feedback style, two instructors perceived changes in the ways they communicated disciplinary knowledge of agronomy and rhetoric through feedback. This finding suggests that collaborating in the learning community and providing cross-feedback enables instructors to learn disciplinary knowledge from one another.;This study extends communication-across-the-curriculum/learning community scholarship and responds to a need for longitudinal feedback research by illustrating how cross-disciplinary collaboration enables instructors to integrate disciplinary knowledge of agronomy and rhetoric in their feedback.