This study explores the perceived impact of a short-term study abroad program on adolescent learners’ intercultural sensitivity and linguistic development. Fourteen Argentinian secondary school students (aged 13–17) participated in a 15-day immersion experience in London, where English functioned primarily as a lingua franca. Upon return, participants completed two post-program questionnaires designed to capture self-perceptions of intercultural and linguistic growth. Findings indicated perceived attitudinal gains in areas such as openness toward difference, cultural respect, and willingness to engage across diversity. Linguistically, students reported improvements in oral fluency and pronunciation, while responses regarding grammar, vocabulary, and listening comprehension showed greater variability. Although these results derive from a small cohort and are based on self-report measures, they point to the formative potential of short-term mobility programs to foster language development and intercultural awareness in adolescent learners. To enhance the pedagogical and evaluative robustness of future programs, it is recommended that task-based reflection, digitally mediated exchanges (e.g., telecollaboration), and pre-and post-program assessments be systematically integrated into program design. Such measures would not only strengthen instructional alignment between linguistic and intercultural aims but also allow for more substantiated claims regarding learner development.