This document discusses mathematical proficiency and what it means for different groups. It defines mathematical proficiency as having five intertwining strands: conceptual understanding, procedural fluency, strategic competence, adaptive reasoning, and productive disposition. These strands were developed by the National Research Council to describe factors of proficiency based on research. The document prompts the reader to consider what proficiency looks like for teachers, students, parents, and employers, and to provide classroom examples of the different proficiency strands.