Background: This study is conducted in Singapore, where learning to read in English is regarded as essential because it is offered as a First Language (L1) subject in the curriculum and is stipulated as the medium of instruction in the education system, and the mother tongues are offered as Second Language (L2) subjects, although the majority still learn English as an L2. Aims: The paper reports on the reading strategies used by Singaporean primary school pupils from a cognitive perspective, which is part of a larger study that aims to investigate these pupils' language learning strategies. Sample: The participants were 18 pupils from three neighbourhood primary schools, in grades Primary 4, 5 and 6. Method: The data were collected from high- and low-proficiency pupils at each of the three grades in each school, who read two texts at each level. Grounded in an information-processing theory and based on successful experiences of scholars using think-aloud for data collection, we asked the pupils to read and report what they were thinking about while reading. The think-aloud protocols were recorded, transcribed verbatim, coded and analysed. Results: The results suggest that participants' flexible and appropriate use of reading strategies varies according to language proficiency and grade level, with the high-proficiency group outperforming its lower-proficiency counterpart and the high-graders outnumbering the lower-graders in terms of the number of strategies that they used. These differences were also exemplified with qualitative findings from case studies. Conclusions: The use of reading strategies differs according to proficiency levels, and the quality of pupils' strategy-use patterns has more significant implications for understanding efficient reading among primary school pupils.