This study examines the effects of self-efficacy, students' effort and access to educational resources, and teachers' development on the achievement of elementary school students in mathematics. Using the 2013 National Assessment of Educational Progress (NAEP) restricted data set, this study determined if and how these three aspects individually and in combination affected performance on the fourth-grade NAEP math assessment. The NAEP is referred to as The Nation's Report Card, guiding educational practice and policy through the assessment of a large, diverse sample from the entire United States (NAEP, 2013a). This non-experimental study addresses the issues of declining test scores in the United States alongside some of the many factors that are thought to contribute to educational achievement (OECD, 2019; NAEP, 2017). By approaching the study through the lens of self-efficacy (Bandura, 1986), constructivism (Bruner, 1960), and mathematical knowledge for teaching (Hill et al., 2005), relevant variables were selected from NAEP, reduced to factors, and used in regression analyses to better understand the ongoing downward trend in international math assessment scores. The findings of this work contribute to the field of education by providing insight into how issues outside the classroom can impact student achievement. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]