A study examined how two international studies--the 1991 International Association for the Evaluation of Educational Achievement (IEA) Reading Literacy Study and the 2001 Progress in International Reading Literacy Study (PIRLS, also conducted by IEA)--compared to each other in the aspects of reading literacy each assessed, the types of texts they used in the assessments, and the types and difficulty of the questions they used. In comparing the frameworks, passages, and items, there were both differences and similarities. The definitions of reading literacy were very similar. The types of passages used were similar but in actually choosing and categorizing passages, the IEA emphasized the types of texts while the PIRLS focused on purposes for reading. The passages/texts on the PIRLS were longer, more engaging, and more complex in most cases. The question taxonomies that were generated to frame the tasks on the assessments were very different. The PIRLS passages were presented in an engaging and authentic manner that might have improved students' motivation to read and respond to the texts. This is one area where the form of the PIRLS might have contributed to students' level of performance. However, if students lacked the skills necessary to respond to the items, engaging texts would not have helped much. With a wider range of skills being called for on the PIRLS than on the IEA, especially skills requiring deeper thinking, it is possible that the results of the 2001 PIRLS will show U.S. students spread out more at the top and a wider distribution of their scores than on the IEA in 1991. Appendixes contain item rating sheets and a description of the levels of depth of knowledge for language arts reading. (RS)