This article revisits the important issue raised by Peter Tymms where he challenges the official government reports of an impressive rise in standards in mathematics and English in primary schools in England since 1995, suggesting that the rise in scores, particularly since 2000, does not indicate rising standards. In order to substantiate its claim the Government has repeatedly referred to the results of an international study which put England in the top three of the 35 participating countries for achievement in reading, the Progress in International Reading Literacy Study (2001). Firstly, the nature of an international comparison which uses a single indicator of achievement is critically examined in terms of the fair comparison and resulting commensurability of very different national school populations. Here issues of cultural bias are raised in relation to the unidimensionality of the reading test items and the contrasting wealth, representational sizes, and varied geographic dispersals of the target populations. Secondly, the PIRLS study is analysed for its potential for linguistic bias. Finally, the PIRLS data for England are examined, where it is shown, in comparison with other countries, the sampling and the test itself to have been advantageously organised. The article concludes with a critical discussion of the validity of known results with regard to the testing of English primary-aged children in literacy. (Contains 3 tables.)