Although many educators have recently discussed the positive effects of flipped learning, there is little empirical evidence about whether this approach can actually promote students' English learning. This study was undertaken in four sections of the same College English 1 (E1) course over two consecutive semesters at a South Korean university. A total of 79 students enrolled in the E1 course participated in the study. Of the participants, 39 learned English using a communicative language teaching approach, whereas 40 studied English in a flipped learning manner. Data were gathered from the students' achievements in three major tasks, their responses to three surveys, and the instructor's notes on the students' engagement in the process of their English learning. Findings demonstrate that the students in the flipped classroom achieved higher average scores in their final three tasks than those in the non-flipped classroom, but only the final examination mean score indicated statistical significance. However, surveys indicated that most students in this study seemed to enjoy learning English in a flipped learning environment. Also, the instructor found the students in the flipped classroom to be more engaged in the learning process than those in the non-flipped classroom. Pedagogical implications for effective English teaching are discussed.