In 2001, Kilpatrick, Swafford, and Findell proposed a new way to look at what it means for students to be mathematically proficient. They described mathematical proficiency as comprising five intertwined strands: procedural fluency, conceptual understanding, adaptive reasoning, strategic competence, and productive disposition. The vision is that these proficiencies develop together, each reinforcing one another and each being critical to a student becoming mathematically proficient. With the advent of the Common Core State Standards for Mathematics (CCSSI) in 2010, four of these strands were expanded and adapted to become part of the eight Standards for Mathematical Practice. Conspicuously absent, however, from these new standards is the strand of mathematical proficiency called "productive disposition." Despite the importance of this strand of mathematical proficiency, productive disposition is mentioned only in the introduction to the Common Core's Standards of Mathematical Practice, not explicitly codified in the eight practices. Because productive disposition is not explicitly built into the Standards for Mathematical Practices, the author's concern is that it seems to be getting left out of the discussion about how we want students to engage in mathematics. At conferences, in classrooms, and in new curriculum materials, we discuss how to help students reason about mathematics, develop conceptual understanding, become strategic problems solvers, and develop procedural fluency. Very seldom do we talk about how to help students develop mathematical dispositions to support these other practices.