This volume was originally inspired by a 2017 conference to honour the scholar and linguist Cao Xuân Ha?o, whose landmark work – in many diverse areas of language study – established a bridge between traditional Vietnamese scholarship and contemporary theories of grammatical organisation. The book offers the reader a closely edited collection of papers, representing a wide spectrum of frameworks, approaches and methods, from traditional fieldwork studies of non-standard dialects, to corpus-based discussions of language and gender, to formal syntactic and semantic analyses of key functional morphemes, to laboratory experiments, and work in first language acquisition. Many of the papers present detailed analyses of original data, as well as novel treatments of established facts; considered together – as well as in contrast to one another – they make a significant empirical contribution to our understanding of how Vietnamese is structured, acquired and put to use. The papers should be of value to anyone interested in contemporary approaches to Vietnamese linguistics, and Southeast Asian languages more generally.