This introductory chapter situates Vietnamese as a rapidly expanding second/foreign language in higher education worldwide, documenting growth across North America, Europe, and Asia and underscoring Vietnamese’s status as a Less Commonly Taught Language. It presents the edited volume Research and Teaching Vietnamese as a Second Language: A Global Perspective as an outcome of the annual Ca’ Foscari–Arizona State symposium (launched in June 2024), designed to connect researchers and teachers and to advance evidence-based pedagogy for both heritage and non-heritage learners. The chapter clarifies key terms (second vs. foreign language; heritage/home language) and foregrounds the affective, ideological, and identity negotiations that shape multilingual classrooms. It highlights translanguaging as a lens and practice for leveraging learners’ full repertoires to promote inclusive instruction and curricula. Emphasizing a “teachers teaching teachers” ethos, the chapter argues that educator-led empirical studies can close research gaps and yield actionable classroom resources, then previews the volume’s four thematic sections.