Study abroad (SA) is typically thought to provide an excellent opportunity for second language acquisition, particularly through exposure to and application of the target language within the target culture. However, actual language gains vary greatly among SA participants and some may gain very little (Freed, 1995a). The purpose of the current study is to determine some specific linguistic gains made by 28 second language learners of Japanese studying for two semesters in Japan, and to determine possible correlates with these gains. Specifically, it addresses whether or not these SA students improve their grammatical proficiency, lexical proficiency, narrative ability, fluency, and pragmatics proficiency. It then explores how language learning aptitude, personality, language use, social networking, and initial ability correlate with those gains. To measure these gains and their correlates it uses the following instruments: the Elicited Imitation task, a picture story, the Pragmatics Self-Assessment, the Non-Word Repetition test, the NEO-Five Factor Inventory, the Language Contact Profile, and the Study Abroad Social Interaction Questionnaire. The results indicated that these SA students improved significantly in at least on measure of grammatical proficiency, lexical proficiency, narrative ability, fluency, and pragmatics proficiency. Initial ability and language use proved to correlate best with each area of linguistic gain; however, the other correlates were also related in certain areas. SA students should prepare to use their language and participate in social networks to best improve their linguistic abilities.