Calculus at the college level has significant potential to serve as a pump for increasing the number of students majoring in STEM fields. It is a foundation course for all STEM majors and, if mastered well, should provide students with a positive and successful first-year experience and gateway into more advanced courses. Studies have shown that a high percentage of students failing college calculus has caused a shortage of individuals entering fields that are heavily dependent on mathematics. Many students are entering college ill-prepared for the rigors of college-level mathematics. This mixed methods study examines the relationship among high school preparation, additional preparation in college, and introductory calculus success. Using a convenience sample of three calculus professors, seven calculus teaching assistants and two hundred and seventy one calculus students at a large public mid-west university in the United States, we investigated the relationship between the amount and level of high school mathematics and student performance in college calculus. Our results suggest that good preparations in high school pre-calculus form a springboard for future success in college calculus as well as subsequent advanced mathematics courses.