This study investigated similarities and differences between L1 and L2 reading strategies of Korean English learners. Twenty-one Korean university students participated in the study. Data was obtained by means of the think-aloud method to identify their L1 and L2 comprehension strategies and their patterns focusing on global, support, and problem-solving strategies. In addition, changes in their strategic behaviors as their reading proficiency develops are further explored. The results revealed overall similarities in the basic trends of sub-strategy use in both L1 and L2 reading but differences in the frequency of strategies used. The findings seem unable to be explicated by the linguistic interdependence hypothesis or the linguistic threshold hypothesis alone. Pedagogical implications for strategy training and raising students’ metacognitive awareness are suggested.