This paper presents a small-scale study examining the effects of metacognitive reading strategy instruction on English language learners' reading comprehension in a Hong Kong international school. Twenty-five primary school (Grade 5) students who learn English as a second language participated in this study. Metacognitive instruction was incorporated into 10 process-based reading lessons. Data were collected from notes learners took during reading, post-reading reflection reports, teacher-facilitated group discussions and two types of reading tests. Results revealed that the young learners could articulate several knowledge factors that influenced their reading. In addition, learners reported a better understanding of the nature and demands of reading, a deeper awareness of metacognitive knowledge in improving reading comprehension and increased confidence in handling reading exercises. The learners also showed enhanced reading performance compared to those in a control group without metacognitive intervention. This study highlights the potential of metacognitive instruction to enhance primary school English learners' reading literacy.