This study explored the influence of school funding and climate on student achievement in Illinois public elementary schools, examining de-identified individual fourth-grade students and their achievement scores during the 2018-19 academic year. Data sources included the Illinois Achievement Readiness (IAR) assessments for reading and math, per-student school-level spending from the Illinois Site-Based Expenditure Report (SBER), and stakeholder perceptions from the Illinois 5Essentials School Climate Survey. Multilevel structural equation modeling was used to analyze the sample, which encompassed 2,056 schools and 137,048 students, a significant portion of the estimated 140,541 fourth-grade students in 2,371 respective schools statewide. Findings indicated that increased funding correlated with improved achievement, while school climate played a crucial and robust role in mediating and moderating this relationship. Schools with a positive climate displayed a strong link between funding and achievement, whereas those with a weak climate showed no significant correlation. Funding alone had a small correlation with achievement (r[superscript 2] = 0.07), while climate emerged as a powerful mediator and moderator (r[superscript 2] = 0.55). The most predictive factors of the 5Eessentials survey were collaborative teachers, effective leaders, and engaged families, respectively. Additionally, some schools were more adept at mitigating the effects of socioeconomic status on achievement. These findings underscore the importance of considering both funding and climate when striving to enhance student achievement. Future research could explore these relationships in different contexts, investigate other factors, and conduct longitudinal studies to evaluate the persistence of effects and the potential diminishing returns. A deeper understanding of these relationships could guide targeted school climate interventions and resource allocation strategies, optimizing student achievement across diverse educational settings. [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.]