Reading for personal interest and acquiring and using information using various reading processes are important parts of reading literacy that students need to develop in order to progress successfully through their schooling and fully function in the information society. Computer assisted reading instructional activities are assumed useful in improving the reading literacy of students, especially reading processes. However, students in Hong Kong and the US demonstrated a substantial performance gap in reading proficiency. Using the data from Progress in International Reading Literacy (PIRLS) 2011, this study examines whether and to what extent four computer-based reading instructional activities influence students' performance in reading processes central to reading for interest and acquiring and using information in Hong Kong and the US. It found that computer-based reading activities are associated with students' literacy performance in different ways in the two places. In particular, the more often Hong Kong students used the computer to read, the lower the reading achievement in all reading processes measured. However, in the US context, using the computer to write is positively associated with students' reading scores in all reading processes while using software is negatively related to their reading performance in using all the reading processes.