The purpose of this quantitative comparative study was to examine if gender and participation in a STEM curriculum have separate and/or interacting statistically significant effects on academic achievement of 8th grade middle school students attending Arizona Title I middle schools. The theoretical foundation was cognitive learning theory, which focused on identifying information processing techniques that contribute to the most efficient and effective learning. The research question asked if gender and participation in a STEM curriculum have separate and/or interacting significant effects on overall academic achievement. In this study, data was analyzed using a two-way ANOVA. There were no statistically significant interaction effects between gender, STEM status and/or academic achievement. The study showed F = 2.936, p = 0.089, [partial eta-squared] = 0.018. for end of year academic achievement scores for females and males. The study showed F = 0.063, p = 0.802, [partial eta-squared] = 0.000 for end of year scores for STEM and non-STEM students. The study showed, F = 0.584, p = 0.446, partial [partial eta-squared] = 0.004 for interaction effect between gender, participation in STEM curriculum, and overall academic achievement. [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.]