An inventory was made of reliable characteristics of effective schools within and across contexts, including a comparison of results of effective-schools research from different nations. A five-factor model of school effectiveness is discussed, which gives the following characteristics: (1) academic goal consensus; (2) safe and orderly climate; (3) strong instructional leadership; (4) high expectations for student achievement; and (5) frequent evaluation of student progress. This model is mainly based on research from the United States. An examination of the Dutch school system and review of studies of school effectiveness in the Netherlands do not support this five-factor model. There was no relation between the characteristics of effectiveness in Anglo-American schools and student dropout rates. The evaluative potential of a school is one characteristic that appears valid across contexts. It is evident that contextual effects must be taken into account in conducting and analyzing research in school effectiveness. A multiple level of school effectiveness should be the conceptual background of individual studies. One figure illustrates the secondary educational system in the Netherlands, and six tables present data descriptive of Dutch school effectiveness. (SLD)