Research on language and mathematics has highlighted how linguistic demands shape students’ opportunities to participate in mathematical activity. Drawing on findings from the Developing Language-Responsive Mathematics Classrooms project this talk describes our work with teachers on recognising and responding to the language challenges embedded in mathematical reasoning representation explanation and argumentation. Communication-responsiveness in mathematics classrooms requires attending to meanings constructed across language symbols diagrams examples and gestures.  I will explore what becomes visible when attention shifts to the relationship among communication meaning-making mathematical structure and coherence and consider the implications for research.