Prior research has established the potential for achievement gains from attending smaller classes. However, large statewide class-size reduction (CSR) policies have not been found to consistently realize such gains. A leading explanation for the disappointing performance of CSR policies is that schools are forced to hire additional teachers of lower quality to meet the new class-size requirements. The first chapter uses administrative data from an anonymous state to explore whether the value-added of newly hired teachers fell after the introduction of CSR. The results suggest that while there was a modest fall in the relative average quality of newly hired teachers and those retained beyond their first year, this drop is not nearly large enough to explain the failure of CSR to produce sizeable achievement gains. Furthermore, schools facing CSR pressure saw similar falls in quality as those that did not, likely due to labor market competition forcing all schools along the effective teacher supply curve. Therefore, between-school differences in the quality of incoming teachers cannot explain the failure of previous quasi-experimental treatment-control comparisons to find achievement effects from statewide CSR. In addition to providing insight into CSR, the results are informative for assessing any potential intervention that may drastically increase the short-run demand for teachers. The next chapter provides necessary background information for the first chapter. Prior evidence for the change in teacher composition associated with CSR policies focused on changes in observable teacher characteristics in California. California experienced large increases in the percentage of teachers without certification, without an advanced degree, and with fewer than three years of experience. These changes in the composition of the teacher workforce in California have been cited when looking at CSR in other states. However, there has been no study of changes in the composition of the teacher workforce in other states. Chapter 2 explores the case of CSR in the state of Florida. Unlike in California, this paper finds little evidence of large changes in teacher characteristics associated with class-size reduction. Only average experience moves in a direction consistent with California's experience. This drop in experience is found to be slightly larger for schools serving larger minority and low-income populations. The third chapter examines the effectiveness of a range of pedagogy practices in kindergarten and first grade using a longitudinal survey dataset. In answering this question, the focus is on concerns over the nonrandom exposure of students to different teaching strategies. The findings indicate that various teaching modalities, such as working with counting manipulatives, using math worksheets, and completing problems on the chalkboard, have positive effects on achievement in kindergarten. In first grade, pedagogical practices relating to explaining problem-solving and working on problems from textbooks have positive effects on achievement. Furthermore, the results suggest that the models and estimators previously employed to estimate teacher characteristic and practice effects using longitudinal survey data likely neglected problems arising from the nonrandom sorting of students and teachers into schools. [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.]