The International Schools' Assessment (ISA) provides an insight into students' proficiency in the three domains of mathematical literacy, reading and writing, in each case derived from a single measure of performance on a particular day. This document is designed to help administrators and teachers interpret the reports provided to schools on their students' performance in the International Schools' Assessment for 2003. This document is about the substance and interpretation of the reports. Appended are: (1) Feedback Form; (2) A Brief Description of the OECD PISA Project; (3) Sample Letter to Parents to Accompany Individual Student Report; and (4) Explanation of Terms.