Online backchannel chat rooms offer the potential to transform classroom learning in unexpected and powerful ways. However, the specific ways in which they can influence teaching pedagogy and learning opportunities are less well understood. Activities in a backchannel may include the dissemination of ideas, knowledge building, asking and answering questions, engaging in critical discourse, and sharing information and resources. This chapter describes a backchannel chat room that has taken place over multiple years in a large university student community. It explores unforeseen and exciting opportunities, as well as possible limitations, for designing teaching and learning practices to leverage this communication medium. With a deeper understanding of the opportunities and limitations of the backchannel, educators and instructional designers could transform the classroom experience from a passive lecture model to one of active, collaborative, and engaged knowledge production.