This study examined the relationships between teacher leadership, science teacher self-efficacy, and fifth-grade science student achievement in diverse schools in a San Antonio, Texas, metropolitan school district. Teachers completed a modified version of the "Leadership Behavior Description Question" (LBDQ) Form XII by Stogdill (1969), the "Science Efficacy and Belief Expectations for Science Teaching" (SEBEST) by Ritter, Boone, and Rubba (2001, January). Students' scores on the "Texas Assessment of Knowledge and Skills" (TAKS) measured fifth-grade science achievement. At the teacher level of analysis multiple regressions showed the following relationships between teachers' science self-efficacy and teacher classroom leadership behaviors and the various teacher and school demographic variables. Predictors of teacher self efficacy beliefs included teacher's level of education, gender, and leadership initiating structure. The only significant predictor of teacher self-efficacy outcome expectancy was gender. Higher teacher self-efficacy beliefs predicted higher leadership initiating structure. At the school level of analysis, higher school levels of percentage of students from low socio-economic backgrounds and higher percentage of limited English proficient students predicted lower school student mean science achievement. These findings suggest a need for continued research to clarify relationships between teacher classroom leadership, science teacher self-efficacy, and student achievement especially at the teacher level of analysis. Findings also indicate the importance of developing instructional methods to address student demographics and their needs so that all students, despite their backgrounds, will achieve in science. [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.]