The purpose of this study was to examine constructivist-based algebra lessons and a cooperative construct to address the achievement gap between White (non-Hispanic) and Mexican American 8th grade students at a southern California middle school. The lessons were designed to facilitate social interdependence which promoted peer-to-peer interaction and co-dependence upon each other for the acquisition of social and logical mathematical knowledge of algebraic concepts in a cooperative setting. Vygostsky's sociocultural theory and Deutsch's social interdependence theory were chosen as theoretical frameworks for this quantitative study. A 2x2 factorial design was employed to answer the key research questions related to a statistically significant mean difference in achievement scores on the Elementary Algebra Diagnostic (EA50A90) test between (a) cooperative learning and traditional instruction, (b) benchmark and strategic student ability levels, and (c) the results from specific interaction between the type of instructions and the student ability levels. A two-factor analysis of variance was used to analyze the EA50A90 pretest and posttest results. In the study findings, there was a statistically significant mean difference between algebra achievement scores on students' posttest among the students who participated in constructivist-based algebra lessons using a cooperative construct and those who received traditional instruction. Social interdependence within cooperative learning group members scaffolded academic success. The results of this study contributed to social change by prompting Algebra I teachers to use a social interdependence process as a vehicle to promote improved Mexican American student 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.]