The federal No Child Left Behind Act requires all students, regardless of gender, race, or socioeconomic status, to be proficient in reading by the year 2014. Although progress has been made, discrepancies in reading achievement remain. Accordingly, the purpose of this study was to investigate the effectiveness of two instructional strategies (Guided Reading and SRA Reading Mastery) on the reading achievement of struggling readers and determine the effect of gender, race, and socioeconomic status on reading achievement according to instructional strategy. An advocacy theoretical framework informed the dual epistemologies of behaviorism and constructivism in this quantitative, quasi-experimental, nonequivalent control-group study. Sixty-six second grade struggling readers from two rural elementary schools comprised the convenience sample that included the use of two treatment groups. Pre, mid, and posttest Measures of Academic Progress (MAP) reading scores were analyzed using a mixed model repeated measures ANOVA. The within-subject factor was time, with type of instruction, gender, socioeconomic status, and race used as between-subject factors. Results indicated a significant main effect of time on reading achievement and a significant interaction between time and instructional strategy for Guided Reading but no significant interactions between instructional strategy and the between-subject factors of gender, race, or socioeconomic status. Recommendations include a study with a larger sample size and an evenly balanced proportion of students in both treatment groups. This study contributed to positive social change by examining curriculum models that lead to gains in reading achievement for struggling readers and those that reduce the achievement gap for males, minorities, and those from poverty.