and three subtests of the Iowa Tests of Basic Skills were administered to 129 second-grade students who had continuous experience in either open classrooms or traditional classrooms as defined by the Walberg-Thomas Open Education Scale. Five classes of each type were studied in three different school systems. Although students in traditional classes in one school system had higher fluency scores than those in open classes, consistent differences in fluency were not found; no significant group effects were found for uniqueness scores. However, students in traditional classrooms scored consistently higher than those in open classrooms on measures of vocabulary, reading, and mathematics achievement.