This paper presents an ethnographic case study exploring second language learners’ use of the social networking site (SNS), Lang-8, in an outside-of-school context. The main purpose of this study is to understand what activities today’s L2 learners perform in the social networking environment for language learning and how they perceive the use of the SNS for L2 learning from an insider’s point of view. Data were collected over a nine-month period from participant-observations, online documents, and interviews with 12 active Lang-8 users. The findings of this study show that participants’ activities in the Lang-8 environment are closely related to the main features of language learning SNSs (e.g., creating a profile, expressing oneself, sending a friendship request, and engaging in peer feedback), which are aimed at initiating and maintaining networks of friends. In addition, participants identified perceived benefits of Lang-8 for language learning in academic, social, and emotional areas. These findings suggest that SNSs specifically designed for language learning can be used to complement classroom-based language teaching and learning environments.