Minority underrepresentation in science, technology, engineering, and mathematics (STEM) perpetuates the income inequality that minorities experience and leads to a lack of diversity in STEM. The purpose of this quantitative nonexperimental study was to examine the effect of student demographics, STEM, science technology, engineering, art, and math (STEAM), and traditional middle school learning environments on student preparedness for the STEM fields as measured by student test scores on the eighth-grade Florida Standards Assessment in math (EGFSAM), in an urban school district in South Florida. I adopted Bandura's (1977) social cognitive theory (SCT), consisting of reciprocal causation elements that stimulate learning as follows: "action" school designation, "interpersonal factors," student test scores and demographics, and "environment" type of learning environment. A hierarchical multiple linear regression analyzed the data (n = 597). Four major results are female students outperform male students by 5.309 points, t(1) = 2.967, = 0.003; STEM middle school students underperform traditional middle school students (TPMS) with 0-10.481 points, t(1) = -4.838, p < 0.00; STEM middle school students demonstrate the highest unique variance on the DV, (-0.195)[superscript 2] = 4%, p = 0.00; and only STEM middle school students demonstrate a statistically significant underperformance. Overall, Model 2 (i.e., all triadic elements) is a better indicator of 21st-century preparedness. The results indicate minority students' 21st-century preparedness occurs at traditional public middle schools, which makes minority students' mathematical aptitude regardless of school type critical. Future research should examine the relationships between minority students' math self-efficacy and actual STEM field preparedness. [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.]