This paper investigates the functions of prosodic phrasing in the Austronesian VSO language Samoan. Two types of sentences are investigated, exclusives (involving the particle na’o ‘only’) and equatives. Two complementary methodologies were used, a production study and an acceptability judgment study, to examine the prosodic realisation and relative naturalness of different word orderings of the two sentence types. The particle na’o has an unusual distribution: preceding the initial constituent, be it the verb or a fronted noun phrase; or following the verb, but only modifying the absolutive (object). It was found that post-verbal absolutives modified by na’o are usually not preceded by a phrase boundary, unlike unmodified absolutives which are consistently preceded by a high phrase tone (H-) (cf. Yu 2009). Equatives in Samoan involve clauses which are the juxtaposition of two noun phrases, one the rheme (focus) and the other the theme (topic). It was found that rhemes are usually followed by a phrase break, while for themes this is optional. Rheme-theme order was strongly preferred to theme-rheme order. These findings are argued to show a close relationship between information structure, constituent ordering and prosodic phrasing in Samoan. The preferred order of constituents in Samoan is rheme-theme, with a high phrase tone marking the end of the rheme. The absolutive argument is strongly preferred to be at the start of the theme.