This study examines opportunities for Korean EFL students at a Korean university to use English as their L2 in their informal social networks. Through interviews as well as analysis of the students’ interactions in an informal environment, the study focuses on the major factors affecting the construction of these opportunities. The findings show that the students expanded their social networks with English speakers during their first year of university. More importantly, the study indicates that the same students sometimes had difficulty constructing interactions in English in these networks. This difficulty can be attributed to various factors, including the learners’ history as an L2 learner/user and some norms in the community where the learners were situated. However, the analysis of L1/L2 selection and its negotiation in their interactions shows that the construction of L2 interactions also appears to be mediated by certain factors, such as accommodated goals of interaction and specific discourse strategies. Research implications are provided at the end of the research paper.