Since studies conducted by the International Association for the Evaluation of Educational Achievement (IEA) have had a dramatic impact on the way in which officials in the United States and the American public think about the performance of our students, it is essential that IEA surveys accurately measure real differences in student performance across comparable populations in participating countries. Although data quality in past IEA studies has sometimes been problematic, the upcoming Third International Mathematics and Science Study (TIMSS) affords the opportunity to develop methods of data presentation that achieve reliable cross-national comparisons. Two issues in particular merit consideration. The first issue is ensuring that field outcomes in participating countries are comparable and representative of a defined target population. A second aspect concerns survey response rates. It will also be necessary to determine how to deal with data when certain standards are not achieved. One chart lists the number of participating systems in the various IEA studies. (SLD)