Research indicates that standards-based mathematics instruction positively supports students' academic development. Although standards documents identify accepted best practices, they do not speak to the impact that students' expectations of the mathematics classroom has on the successful implementation of standards-based instruction at the university level. Using a mixed-methods approach, this study investigates those challenges with an iterative self-study of one undergraduate mathematics classroom that seeks to answer the question: How can postsecondary teachers change the expected classroom culture of lecture and practice to new sociomathematical norms that (a) support a community of learners and (b) help students develop a productive disposition toward mathematics within these new norms? An analysis of classroom interactions, students' work, and researcher reflections reveals the need for these changes to be (a) executed over time with attention to students' thoughts and needs and (b) supported with learning tools that provide structure to sometimes seemingly chaotic lessons. The study also highlights the need for teacher support in the form of collaboration, teacher professional development, and reflection.