There is an abundance of research associated with the belief that factors such as educational expenditures, socioeconomic demographics, geographic location, district size and school funding have a relationship to student achievement. This study provides insight into the relationship between these factors and the effect it has on student academic achievement on the ACT. The study design is a causal-comparative (ex-post facto) analysis. The analyses conducted involve two primary variables, instructional and operational expenditures per pupil, and several intervening variables; district size, district location, percentage of dollars received from primary funding sources, and low-income students. A review of the literature covering historical factors that have influenced public education, national and state level reform movements, philosophical methods of funding public education, and the relationship between funding and achievement is included. The data used in the study was obtained from the 2014 Illinois School Report Card database as reported by each district to the Illinois State Board of Education. Only public high school districts were examined. The study determined that the dollars spent on instruction are related to student performance to a highly statistically significant level. Additionally, all examined variables, to some degree, relate to student ACT performance at a statistically significant level. Most importantly, the study found that while the socioeconomic level of the district was by far the strongest predictor of academic performance, the addition of information about the level of instructional spending added a substantial amount of explanation of student ACT performance levels. The findings of the study support the importance of instructional expenditures in generating positive academic performance results at the high school level. [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.]