This study aims to investigate reading strategies and factors affecting the use of strategies of Thai EFL English majors who enrolled in public and private universities in the Bangkok Metropolitan area. The participants were 482 male and female college students and the study used both quantitative and qualitative analysis. In addition to using the Survey of Reading Strategies (SORS) invented by Shoerey and Mokhtari (2002), think-aloud protocols, retrospective interviews, and document study were used to gain in-depth information of how 12 volunteered participants thought while reading English academic texts. The quantitative results demonstrated that the participants used a combination of reading strategies but the Cognitive strategy category seemed to be the most reported strategies as used. Overall, the factors affecting the use of reading strategy were the instructional type and the self-rated reading ability type. According to the Metacognitive category, there were three factors affecting the use of such strategies. Those were 1) the instructional type, 2) the length of time spent studying English, and 3) the self-rated reading ability. On the other hand, there was only one factor that affected the use of Cognitive and Support strategies, that is, the self-rated reading ability. In addition, qualitative data showed that the English proficiency levels, the school years, the opportunity to use English, and the instructional type affected the participants’ strategy use.