Facilitating students' transition from less to more mathematically productive engagement in discussions is an important area of investigation. Research on mathematical whole-class discussions has consistently identified facilitating students' mathematical autonomy as a central component of this transition. Additionally, research commonly infers such transitions take time to manifest. The present study examined students' perceived mathematical autonomy and perceived engagement in mathematical discussions over a half year of school. Using hierarchical linear growth-curve modeling, the authors found that although it may take time for students to transition into more mathematically productive engagement in discussions, it may be the development of their mathematical autonomy, rather than mere exposure over time, that facilitates this transition.