The study utilized the National Education Longitudinal Study of 1988 (NELS:88) to identify which characteristics of academically effective high schools are key determinants of students' academic readiness for college. A multilevel analysis shows that high school characteristics affect student preparation for college in four core subject areas: reading, math, science, and history. In addition, prior academic achievement is the strongest predictor of academic readiness, followed by high school socioeconomic status and high school climate. Results indicate that students attending schools where academics are emphasized are more likely to succeed, suggesting a systematic link between student achievement and academic climate. (Contains 1 table.)