This paper investigates the ‘only’construction in Vietnamese and its theoretical implications for a particular analysis of association with focus constructions in the literature, namely the bipartite analysis (Lee 2005; Horvath 2007; Cable 2010; Barbiers 2014; Quek and Hirsch 2017, among others). A bipartite analysis, as indicated by its name, assumes that a sentence with an overt focus operator such as ‘only’underlyingly involves two heads in its structure: one on the clausal spine (Op), and one more local to the focused constituent (F). For instance, English only-sentences in (1) are analyzed as a bipartite structure as in (2), with either Op head or F head being pronounced.(1) a. Haki ate only [a fish] F. b. Haki only ate [a fish] F.