Research is needed that gives special attention to the experiences of mathematics teachers of Non-English-Speaking-Background (NESB) students. This need prompted me to investigate four of my tertiary mathematics classes that included a number of NESB students, through practitioner research. The main data collection methods for the study were audio-taping classroom discussions, journaling of my experiences, and student group interviews. The data were analysed around three main domains: classroom social norms, sociomathematical norms and classroom mathematical practices. The first key finding was that NESB students can shift from being less-active to more active participants in mathematical activity when the teacher works with them to jointly constitute classroom social norms that attach importance to, make it safe to and encourage student participation. In this study, these were volunteering to share ideas, explaining and justifying contributions, and asking questions. Establishing these social norms occurs gradually, and NESB students can adopt them over time. The second key finding indicates that changes can occur in strategies NESB students use to solve mathematics problems that are embedded in everyday contexts, if they are involved in the joint construction of sociomathematical norms that value the negotiation of mathematical meaning. Over time, and with support, students can develop the ability to support their thinking, and come to understand what counts as mathematical problem-analysis, explaining and justifying mathematically, and communicating mathematically. The authority to evaluate the authenticity of mathematical contributions can be distributed among NESB students and between students and the teacher, if students are positioned as creators and evaluators of mathematical knowledge. The third key finding is that the specific ways of acting and reasoning that are appropriate for a particular mathematics topic evolve when the teacher and NESB students discuss problems and solutions related to that specific mathematical idea. Instead of relying on memorized procedures for solving problems, students progressively rely on their conceptual understanding of specific mathematical ideas and practices. The findings challenge the general view that NESB students will necessarily be passive and prefer to learn by memorising information. They indicate that NESB students can develop as active learners, embracing expectations and obligations that they will contribute ideas and negotiate meaning, rather than follow what the teacher says. Over time, a number of my NESB students developed autonomy in mathematical problem solving and their ability to solve mathematics problems and contribute to class discussion improved. In light of the findings, I propose that NESB students’ mathematics learning may be enhanced by a focus on initiating and guiding joint constitution of classroom social norms that value and encourage student participation in the social construction of knowledge and sociomathematical norms that promote conceptual understanding through negotiation of mathematical meaning. I further propose that NESB students’ mathematics learning may be supported by guiding collective construction of classroom mathematical practices concerned with the specific ways of reasoning and acting needed in particular mathematics topics. The findings of this study have relevance and offer fresh insights for mathematics teachers, researchers and tertiary institutions into how NESB students can be supported to learn mathematics. Further research in this area could examine practices of other mathematics teachers involved with NESB students.