Evidence suggests that short-term study abroad experiences can help advance various dimensions of second language (L2) learners' linguistic competence. However, the extent to which gains following a brief sojourn are durable and maintained after immersion remains an open question. The present study examined both the immediate and sustained learning outcomes following a short-term study abroad program by considering L2 Spanish learners' (a) linguistic gains in global proficiency, oral production, and L2 knowledge, and (b) nonlinguistic gains in perceived psychobehavioral flexibility, a trait that remains under-researched despite its broad relevance to study abroad contexts. Data were collected at the onset and end of a summer study abroad program in Spain, as well as 5 weeks post-sojourn, after students' reimmersion in the first language environment. Mixed-effects models revealed that gains in global proficiency and some aspects of oral production and L2 knowledge, as well as increases in perceived psychobehavioral flexibility, were noticeable at the end of the program and were maintained for several weeks post-sojourn in the absence of further L2 instruction. Findings provide a first look into the potential of short-term study abroad for promoting durable developmental changes across linguistic and nonlinguistic domains.