Computer-assisted pronunciation training (CAPT) software provides language learners with an individualized free environment where they can have access to unlimited input and repetitive practice pronunciation at their own pace. This study explores the impact of CAPT on 90 Taiwanese college students' pronunciation learning and examines if other kinds of mediation, such as peer support, could enhance its effect. It includes two experimental groups using "MyET," a CAPT program designed in Taiwan, either independently (i.e., the Self-Access CAPT Group) or with peers (i.e., the Collaborative CAPT Group) while the control group only had access to MP3 files for practice. Though the quantitative results did not indicate group difference, the qualitative analysis showed that all three groups went through different learning processes. The Self-Access CAPT Group reported the most frequency in the category of "self-monitoring of language learning and production" while the Collaborative CAPT Group had the most frequency in the categories of "gains and strategies." Lacking the mediation of peers and the feedback from "MyET," the MP3 Group reported the highest frequency in "difficulties" and the least frequency of "gains and strategies" during the practice. Some pedagogical implications are also presented.