College and university admissions offices publish the numbers of "college preparatory" courses they recommend. However, they typically fail to publish how well students should perform in high school courses in order to succeed in college. This study assess the relationship between high school course performance and college performance. A strong relationship was found between poor performance in high school courses and lesser success in college (as measured by first-term college GPA and first-year retention). The common admissions recommendation that students take 16 courses of college-preparatory coursework is perhaps necessary but not sufficient for helping students succeed and helping institutions achieve high success rates. (Contains 5 tables and 2 figures.)