The purpose of this study was to examine science assessment data as generated by the 2005 National Assessment of Educational Progress (NAEP), and through the analysis of four research variables: teaching practices, teacher background characteristics, school conditions, and student characteristics, determine their relationship to science achievement of fourth grade students (Cavanagh, 2006) in the state of California. All children are born ready and willing to learn but as they progress to and through the primary grades, many lose their natural curiosity and enthusiasm for learning (Carnegie Corporation of New York, 1994). By the fourth grade, the performance of most children in the United States (U.S. Department of Education, 2004b) is below what it should be for the nation and is below the achievement levels of children in competing countries (Carnegie Corporation of New York). We must trust children to learn if given the chance (Bush, 2008). The analysis of these research variables found that there are relationships between teaching practices, teacher background characteristics, school conditions, student characteristics and science achievement of fourth grade students in the state of California. Revelation of these relationships provide a deeper understanding of the science achievement gap between privileged and underprivileged school children. The utilization of these findings in the classroom will lead to increasing science achievement in all student groups and notably help to decrease the achievement gap between privileged and underprivileged students. Policy changes are suggested at the district, regional, and national levels to close the international achievement gap. [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/en-US/products/dissertations/individuals.shtml.]