Becoming mathematically literate means not only knowledge of the content of mathematics but also understanding of the nature of mathematics and the literate practices involved in the creation, communication, and consumption of its content. This case study examined one mathematician’s view of the nature of mathematics and his literate practices. Data collected include semi-structured interviews with the mathematician, observations of his daily work routines, and his think-alouds during the reading of a disciplinary text. These data were analyzed qualitatively through an iterative process involving multiple readings and identification and refinement of codes. The analysis revealed that the mathematician (a) viewed mathematics as rigorous and demanding, both theoretical and practical, relatively stable but highly rewarding, interconnected with other disciplines, and involving discipline-legitimated discursive practices; (b) engaged in extensive reading/viewing and writing, valued learning from repeated trials and errors, and collaborated with an international network of peers in research; (c) used a range of reading strategies (e.g. close reading, summarizing, questioning, storying, evaluating, annotating) to help him make sense of the disciplinary text; and (d) marshaled both verbal and visual resources to create specialized knowledge, engage in rigorous reasoning, develop logical argument, and construct professional identity. These findings provide important insights that can help teachers design activities that are authentic to mathematics practices and effective for promoting mathematics literacy.