The author examines the effects of different introductory microeconomics textbooks on student performance in subsequent economics courses (specifically, Intermediate Microeconomics I and Money and Banking). In some cases, the effects are significant and sizeable. There is also evidence of other variables affecting student performance in later courses, such as taking first-year microeconomics by distance, math background, effects of having taken other economics courses, and the time between introductory economics and later courses. (Contains 5 tables and 19 notes.)