Students need to develop scientific literacy in order to participate fully as citizens, community members, and in the globalized economy. But what is the relationship between scientific literacy and reading literacy? Three international data sets from the Programme on International Student Assessment (PISA) were used to calculate correlations between scientific literacy and reading literacy for 15-year-old students. Mean correlations at the individual student level across countries were .840 for the PISA 2000 data set, .805 for the PISA 2003 data set, and .819 for the PISA 2006 data set. In all three data sets, this correlation varied among countries, and the reading-science relationship was weakest in countries with low country mean reading scores. Three possible interpretations are discussed, favoring the interpretation that knowledge and skills that drive higher reading comprehension also drive higher science achievement.