Sociologists have long used educational expectations to understand the complex mental processes underlying individuals' educational decision making. Yet, little research evaluates how students actually formulate their educational expectations. Status attainment theory asserts that students adopt their educational expectations early based on family background and social influences, and that their educational expectations are driven by a static mental construct as a result. In contrast, recent research based on Bayesian learning theory hypothesizes that students mostly adapt their educational expectations in light of new information about their academic potential. Comparing models of expectations formation in adolescence, we find that students' expectations do not derive from a static mental construct. However, students adapt their educational expectations only modestly and only in response to very large changes in grade point averages. Thus, adolescent educational expectations stabilize early and are rather persistent over time.