Shifting classroom discourse to be more student-centered has become an integral part of reform-oriented instructional practices. At the same time, shifting discourse can open up opportunities for inequity to occur in the immediate learning environment as both the quantity and quality of mathematical talk changes. In this project, I examined complexities involved in such settings by using discourse analysis methods to explore the positioning of students relative to mathematics content and each other's mathematical ideas. First, I analyzed the ways teachers' discourse during group work enactments related to established equitable teaching practices. Findings from this study suggest communicating group tasks as open may afford teachers more opportunities to enact known teaching practices that support equitable group work (e.g., focusing on sense making, using roles to structure participation). Second, using constructs from positioning theory and anti-deficit perspectives, I analyzed student and teacher discourse on a micro-timescale during a whole-class standards-based mathematics discussion. Results from this study provide a counter-story narrative illustrating how one Black girl's forms of resilience emerged from interactions as she resisted against micro-invalidations of her mathematical thinking. In particular, sense making and silence were forms of resilience that emerged through repeated acts of resistance, which were evidenced by negotiated or rejected positions. Broadly, this dissertation project supports ongoing calls to critically examine teaching practices situated in reformed mathematics instructional contexts. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]