The purpose of this quantitative study was to examine the influence of social-emotional competence (SEC) and various other student- and school-level variables on the academic achievement of kindergarteners. Data were collected on a nationally representative cohort of kindergarteners as part of the United States Department of Education's Early Childhood Longitudinal Study (ECLS-K: 2011) beginning in fall 2010 (n = 18,174). As part of the ECLS-K: 2011, students were assessed via a wide range of sources of information about the children's development, early learning, and school progress. The obtained data were analyzed via Hierarchical Linear Modeling to investigate the influence of student- and teacher-level factors on student achievement. The study found the following: 1) that there was a significant amount of variability in children's mathematics and reading achievement in spring of kindergarten that is explained by school-level variables, as opposed to student-level variables; 2) that children's membership in particular racial groups, gender categories, and socioeconomic statuses all resulted in significant within-school mathematics and reading achievement gaps in spring of kindergarten, controlling for various student background characteristics; 3) that various school-level variables significantly contributed to models predicting children's spring kindergarten mathematics and reading achievement; and 4) children's poverty interacted with their school membership to affect spring kindergarten mathematics and reading 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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]