Several empirical studies and syntheses of extensive reading have concluded that extensive reading has positive impacts on language learning in second- and foreign-language settings. However, many of the studies contained methodological or curricular limitations, raising questions about the asserted positive effects of extensive reading. The present research adds to the limited set of well-controlled studies by investigating the impact of an extensive reading approach over a 15-week semester on the reading comprehension, reading rate, and vocabulary acquisition of Korean university students studying English as a foreign language. A quasi-experimental research design was employed using four intact classes: two control (n = 88) and two experimental (n = 83). The control classes received 100-minute intensive reading instruction per week, whereas the experimental classes received equivalent 70-minute intensive reading instruction and 30-minute extensive reading instruction per week. A repeated-measures multivariate analysis of variance revealed that the experimental classes significantly outperformed the control classes on the combination of the three dependent variables (i.e., reading comprehension, reading rate, vocabulary acquisition). Subsequent analyses of variance confirmed the positive impacts of extensive reading on all three areas. Instructional implications for extensive reading in second-language curricula are discussed.