This is a causal comparative research study that investigates the effects of poverty on student academic achievement within various subgroups in Nassau and Suffolk counties on Long Island, NY. Existing data for approximately 124 school districts from the published New York State Report Card (NYSRC) were used to operationalize the study. The percentage of fourth and eighth grade students scoring a 3 or higher or higher on New York State's math and ELA tests were compared in two ways. One comparison was a cohort study that compared academic outcomes between the 2009-2010 and 2010-2011 school years to examine the stability of academic outcomes for students identified as living in poverty. The second comparison was among schools districts classified by New York State as "Low Need," "Average Need," and "High Need" on Long Island. The research design includes correlations and linear regression analyses to examine relationships of poverty and related variables to student performance in "Low," "Average," and "High Need" districts. Data are compared between the 2009-2010 and 2010- 2011 school years based on fourth and eighth grade math and ELA scores of economically disadvantaged students versus those who are not disadvantaged, general education students versus students with disabilities, and students described as English proficient versus limited English proficient. The same comparisons of student achievement by race/ethnicity were also made: White versus Black/African American; White versus Hispanic/Latino; White versus Asian; Black/African American versus Hispanic/Latino; Black/African American versus Asian; and Hispanic/Latino versus Asian. The results appear to show that, on Long Island, students' chances for academic success are closely tied to the economic classification of their school district. [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.]