Many international students are isolated from their host national peers and suffer loneliness and depression as a result. This study examined faculty explanations for international graduate students' isolation because faculty are in a unique position to observe and interact with both international and host national students as they spend time learning and working together within their academic department. Faculty believed that international students' strong ties with co-nationals, their weak English language skills, and their lack of time to invest in friendships all played a role in their isolation. They also identified host national students' friendship preferences and structural barriers as contributing factors. Faculty observations generally supported previous findings, however, one important difference is discussed in light of differing cultural norms regarding friendships.