At a time when most students aspire for college but not all necessarily attain it, do educational expectations still matter? High self-expectations are said to influence future educational success, but studies have often focussed on expectations at a single point in time. Thus, this research asks how stable, unstable, and later expectations predict students' educational attainment. Using a longitudinal dataset of tenth-grade US students in 2002 (n = 15,244), the research finds that rising and stable high expectations increase the likelihood of entering and graduating from college. However, the opposite is true for those with falling and volatile low expectations, since expectations have marginal effects on predicting entrance to college but have stronger effects on preventing graduation. These findings suggest the salience of "expectation stability", and the need to help students sustain and manage their expectations.