Unlike previous research on participation in mathematics classrooms that focuses on the teacher's role eliciting student talk, the purpose of this dissertation is to study the interactive process through which a teacher connected her reflection and practice, fostering transformations in the culture of participation in a third-grade Spanish immersion mathematics classroom. I draw on hermeneutic listening (Davis, 1996) to understand the teacher's departure from listening for predetermined ways of participating. Methods from participatory design research with children (Bang & Vossoughi, 2016; Groundwater-Smith et al., 2014) and analytical tools from social semiotics (van Leeuwen, 2005) informed the collaborative design and analysis of interventions intended to promote a more inclusive culture of participation. Findings indicate that bringing the students' and the teachers' perspectives on participation into dialogue helped the teacher broaden her ideas on participation. A prolonged, iterative process was necessary to connect these reflections to a practice where the teacher learned to listen hermeneutically for participation. This process started with teacher-researcher co-designed interventions and continued as the teacher recognized participation in unexpected places and moments. The culture of participation evolved toward embracing multiple ways of participating in cooperative mathematical activity in which the students and the teacher addressed unanticipated ideas that emerged in interactions. I describe the semiotic innovations that characterized these transformations and the contextual influences that mediated semiotic innovation. I discuss implications for mathematics education research and teacher professional development. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]