An overview is presented of the scope and findings of the International Association for the Evaluation of Educational Achievement (IEA) studies, which analyzed student achievement in 22 nations, one of which was the United States. Using these findings, this paper identifies national differences in the performance of pupils representing the United States and other nations which are part of a set of relatively more developed countries. Three principal considerations in the differences found--time spent on the subject, curriculum content, and student, teacher, and family expectations--are discussed, along with the principal findings: (1) Among more advanced countries and students, there were no marked deviations in the pattern of achievement test scores; (2) Time given to instruction and opportunity to learn were two key characteristics associated with high test scores and achievement; (3) Curriculum content was consistently and significantly related to achievement scores in the less developed countries and to only a slightly smaller degree in the more developed countries; and (4) Inferences with respect to the place of expectations in student achievement were largely limited to personal expectations and motivation of the individual student. (JD)