Today, many students learn to speak a foreign language by listening to and repeating pre-recorded materials. This is due to the lack of practice opportunities with human partners. Leveraging recent advancements in AI, Speech, and NLP, we developed EnglishBot, a language learning chatbot that converses with students interactively on college-related topics and provides adaptive feedback. We evaluated EnglishBot against a traditional listen-and-repeat interface with 56 Chinese college students through two six-day user studies under both voluntary and fixed-usage conditions. Results show that students were more engaged with EnglishBot and voluntarily spent 2.1 times more time interacting with it. Students’ fluency also improved more with EnglishBot under the IELTS grading standard. Our results suggest that chatbots are an effective learning tool to engage students and have great potential to enhance foreign learners’ speaking abilities.