This investigative research focuses on the level of readiness of Science, Technology, Engineering, and Mathematics (STEM) students entering Historically Black Colleges and Universities (HBCU) in the college Calculus sequence. Calculus is a fundamental course for STEM courses. The level of readiness of the students for Calculus can very well play a huge part in their success in the Calculus courses, higher level college mathematics courses, and other STEM courses. There are many other factors that play a part in how well students perform in Calculus. However, high school mathematics curricula, The American College Test (ACT) scores, and gender were the main foci in this study. A mixed methodology was employed to evaluate the calculus sequence performance of STEM students who participated in the Historically Black College and University Program for the Pre-Calculus Course (HBCU-UP PAC) while they were juniors or seniors in high school. The quantitative method consisted of various statistical analyses such as a Pearson and Spearman correlation, multiple linear regressions, ANOVA, and chi square statistic. Findings revealed that the students who performed well in Pre-Calculus were most likely to perform well in Calculus I and II, the students who performed well in Pre-Calculus were more likely to have performed well on the ACT mathematics section, the students' ACT mathematics score was not a good predictor for their Calculus sequence performance, and the male students performed slightly better than the female students in the Calculus III course. The qualitative method explored the point of views of calculus instructors and students in the calculus sequence through individual interviews. The results of the findings can aid in the development of future programs like HBCU-UP PAC and in developing further studies pertaining to college students' performances in the Calculus sequence. Other factors that were divulged from the interview responses; such as students' study habits, work schedule, possession of the course materials, home life, practicing homework problems, and more can be focuses for future studies. [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.]