This article focuses on the role of history in shaping learning interactions in a high school mathematics class, in which we argue that students participate in two key activity systems: Learning mathematics and doing school. Within the context of these two activity systems, we highlight the nature of "sociogenesis," the patterns of shift in communities as people build on one another's accomplishments, jointly solve problems, and disseminate new and old ways of solving problems. Drawing on a yearlong study of group work in a high school mathematics classroom in California, we discuss how mathematical inscriptions in the classroom and the group's mathematical interactions were influenced by and also influenced the group's shared history. With this article we contribute to cultural-historical activity theory by providing insights into the study of history in classroom interactions. (Contains 1 table and 5 figures.)