This study uses data collected from children in Hong Kong for the PIRLS international reading survey of 2001. A total of 4867 students aged 9 to 10 years from 147 primary schools were assessed. The aim of the study is to investigate the observed differences in comprehension skills displayed in the test results from students at three ability levels. Affective factors (attitudes and reading self‐concept) are also compared for the three groups. Results indicate that the lower‐ability students performed very poorly in all four processes of comprehension — even at the most basic level of retrieval of facts. This weakness at the lower level greatly impaired the students’ ability to operate at higher levels of comprehension involving inference, prediction, integration of ideas and critical evaluation. The weakest readers had extreme difficulty with test items requiring an extended written response. Even on simple multiple‐choice items their performance was inferior to the average and higher‐ability groups. Data from the supplementary questionnaires indicates that across all ability groups the children's attitude toward reading is correlated positively with reading achievement. However, data collected on the students’ reading self‐concept produced anomalous results that cast some doubt on the feasibility of using self‐evaluation and self‐report questionnaires with this age and cultural group. Practical implications from the findings are discussed.