This study examines the relationship between delivery models (the class size reduction model and the sheltered instruction model) and language development levels on the grade-level reading development of sixth-grade English learners (ELs) attending public middle schools in metro Atlanta, Georgia. The instrument used to measure grade-level mastery of reading standards and development is Georgia's sixth-grade Criterion-Referenced Competency Test (CRCT). Language development levels are measured and provided by the Assessing Comprehension and Communication in English State-to-State (ACCESS) test. Criterion sampling and convenience sampling are the means by which ELs are selected. A causal-comparative design was implemented for both research questions. Interaction effects were identified between independent variables of delivery models and language development levels. Main effects between each independent variable and the dependent variable were analyzed for statistically significant differences. Data analysis consisted of a two-way ANOVA, followed by normality and assumption testing. Descriptive data, including demographic and linguistic data, was discussed as well. [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.]