This chapter describes an inquiry into how Japanese university students who have participated in study-abroad negotiate their identity on Social Networking Sites (SNSs) when interacting informally in English with non-Japanese interlocutors. SNSs provide a unique opportunity for English language learners to practise their skills in an informal environment, and to maintain and develop social connections with non-Japanese partners. However, maintaining one's unique identity in these intercultural exchanges can prove difficult. The results of this research showed that a study abroad experience had an influence on students' usage of SNSs in English. This was evident in participants' selecting SNSs that were more commonly used in the country where they studied and adopting non-Japanese behaviours on these platforms. Participants expressed that a fear of flaunting their English ability acted as a barrier to usage, but the effects of this factor was reduced after their time abroad. Finally, participants found that cultural differences in the usage of SNSs caused some tensions, and forced them to evaluate their own cultural preferences and decide what behaviours to adopt from the target culture. While several studies have investigated SNSs for language learning (Ottoson, 2014; Waragai et al., 2014), few have explored identity negotiation in this context (Harrison & Thomas, 2009). Therefore, the following inquiry fills a critical gap in the research literature regarding this topic. [For the complete volume, "Professional Development in CALL: A Selection of Papers," see ED593926.]