Linking IEA's international reading assessments across 40 years is an interesting endeavor from several perspectives. Being able to examine trends in reading achievement at the 4th grade over such a long period and relate these to policy changes during that time span is an attractive idea. However, this work brings to the fore many thorny issues that should be considered in linking together several disparate assessments, and the technical complexities involved in using IRT scaling to analyze trends in large-scale international assessments.