This chapter gives a brief overview on the use of social network sites (SNSs) for language learning and presents an empirical study of the use of Instagram (IG), one of the most popular SNSs, to assess learners' oral communication skills in the foreign language classroom. Several studies have mainly revealed the perceptions and preferences of learners in regards to using SNSs for learning grammar, vocabulary, L2 writing, reading, and speaking. In the current study, the performance scores of participants on an oral communication speaking task delivered both on IG and in class, as well as their scores on the Big Five personality traits as measured by the Quick Big Five Personality Test (QBFPT), were examined statistically. The results demonstrate IG facilitated students' performance in oral communication skill significantly and that personality traits do not predict the performance on IG, but the extroverted and conscientious are highly likely to achieve high scores in classroom.