The purpose of the present study was to examine validity aspects of teachers' judgements of pupils' reading skills. Data come from Sweden's participation in the Progress in International Reading Literacy Study (PIRLS) 2001, for Grades 3 and 4. For pupils at the same achievement levels, as measured by PIRLS 2001 test, teachers' judgements of pupils' achievement levels varied from one teacher to another. Moreover, there were significant differences between teachers' judgements in Grades 3 and 4. Teachers in Grade 3 who had taught their pupils for almost 3 years showed higher correspondence between their judgements and pupil achievement within classrooms than 4th-grade teachers who, typically, had only taught their pupils for approximately 1 semester at the time of the data collection. The results indicate that teachers' judgements and tests can be useful within classrooms, but that teachers may need external assessments to calibrate judgements over classrooms. (Contains 4 tables and 4 figures.)