The purpose of this study was to determine whether academic achievement differed among the Piagetian cognitive levels of 670 students in teacher-education and whether these differences interacted with sex, age, classification (e.g., freshmen, sophomores), or American College Test scores. All were enrolled in a developmental psychology class. Analysis indicated Piagetian scores differed according to sex and American College Test scores but not classification or age; the four types of achievement (quizzes, projects, test, and total) differed according to Piagetian scores, sex, and American College Test scores. All types of achievement except quizzes differed by classification. Age was not related to achievement.