In general, second language (L2) learners have limited vocabulary knowledge. In addition, they often have difficulty identifying, recognizing, or recalling the vocabulary necessary for a certain situation. This limitation and those three factors result in problematic talk where repair, improvement, and practice are merited. The purpose of the present study, following a conversation analytic (CA) perspective, explores how vocabulary-related communication problems are resolved when a low proficient learner (LPL) and a high proficient learner (HPL) communicate during their pair-work activities. In particular, this research studies the sequence of turns and repair in the talk. The study revealed that (1) the repair is mostly initiated by the LPL, (2) the HPL can be a crucial language source in the classroom, and (3) problems are caused by insufficient vocabulary knowledge and not comprehending a correctly-pronounced word. This study reveals the importance of students’ pair-work (especially pair-work activities when the students have disparate English proficiency) in the language classroom and suggests communication strategies.