In the United States, calls for improved K-12 learning opportunities in mathematics have shifted focus in school district offices from bureaucratic pursuits to instructional improvement efforts. Yet, district leaders often receive little guidance on how to achieve these goals. Further, although widely recognized that content-specificity matters in instructional improvement efforts, mathematics-based district leadership has received relatively limited attention in the literature. In this qualitative study, we drew on district leaders' narratives of their work to examine: (1) How do district-level mathematics specialists engage in and make sense of their practice? and (2) What influences the ways they make sense of their practice? Results indicate that the ways in which participants made sense of their leadership practices through their agency, agenda, and positioning was strongly influenced by both personal and systemic factors. Personal factors included the leaders' personal and professional backgrounds and experiences. Systemic factors included the degree of coherence leaders perceived in the district's vision of instructional improvement, the clarity of the district leader's role, and management of staffing resources for improving mathematics instruction. The study concludes with implications for further research and practice.