Book excerpt: Proficiency in mathematics is essential for success in college, career, and life (Reyna & Brainherd, 2007). As a nation, the United States has struggled for decades to strengthen math achievement and to define proficiency in math (Schoenfeld, 2004). An important but often overlooked component of proficiency is math disposition (Kilpatrick, Swafford, & Findell, 2001; NCTM, 1989). Students who lack a productive math disposition often exhibit lower performance in math, lack academic self-efficacy, suffer from math anxiety, and do not pursue higher levels of mathematics (Boaler, 2014; Bouchey & Harter, 2005; Fennema & Sherman, 1978; Reyes, 1984). The purpose of this sequential, explanatory, mixed methods study was to examine the relationship between classroom learning environment (CLE) and the math disposition of third graders attending public schools in a small, suburban district in the Northeast. The study assessed students’ perceptions of classroom environment and math disposition through a combination of surveys and responsive interviews (Rubin & Rubin, 2011). While interest in the area of learning dispositions has increased, few studies have focused on elementary students in the United States. The following research questions were explored: 1. What is the relationship between classroom learning environment (personalization, participation, independence, investigation and differentiation) and disposition (enjoyment of mathematics and self-efficacy) in mathematics? 2. Is there a significant difference between males and females with respect to disposition in mathematics? 3. Is there a significant difference between males and females with respect to classroom learning environments? 4. To what extent and in what manner is variability in self-efficacy explained by classroom learning environment? 5. How do students describe elements of classroom learning environment that contribute to productive math disposition? This study sought to expand the body of research regarding how CLE relates to math disposition. Significant finding were found relating to personalization, participation, and independence, and four salient themese emerged. Educators may benefit from understanding how these elements of classroom enviroment may relate to productive math disposition (PMD). By improving CLE, more students may delelop PMD, which may lead to more enjoyment of math and greater interest in higher-level mathematics.