Introductory Psychology (Intro Psych) is an incredibly popular gateway course, but one that poses notable difficulties for students. These challenges may put international students, such as those from East/Southeast Asia (E/SEA), at a relative disadvantage in the course. English-language proficiency represents a possible resource for E/SEA international students in Intro Psych. However, the specific nature of the relation between English-language proficiency and Intro Psych performance is not well understood. Our hypotheses tested, with increasing precision, the extent to which E/SEA international students suffer more in Intro Psych and the potential role of language proficiency in their performance. Compared to both American-born (n = 715) and immigrant students (n = 145), E/SEA international students (n = 326) earned lower grades in Intro Psych. Unlike the other student groups, E/SEA international students earned lower grades in Intro Psych than in other courses in general. Further, in Intro Psych, E/SEA international students with lower English-language proficiency performed below those with higher proficiency. This proficiency-based difference was stronger in Intro Psych than in other courses in general and held only for E/SEA international students, not immigrant students who were also nonnative English speakers. These results suggest that E/SEA international students—particularly those with less-strong language skills—face a unique vulnerability in Intro Psych, one that is not shared by other students and that does not generally extend to other courses in which they enroll. This has implications for addressing the challenges that international students face and reducing barriers to student learning in Intro Psych.