In Mantauran (Rukai), noun+noun structures are not easy to identify as compounds or nominal juxtapositions. According to Zeitoun (2007), these two constructions share certain structural similarities. Linking elements such as the coordinator la ‘and’ usually do not intervene between the two nominal constituents. They exhibit free word order and bear independent lexical stresses. They differ in that the head of compounds cannot take the genitive pronoun and cannot be coordinated. A more refined investigation is required to validate Zeitoun’s (2007) analysis, however. Further pieces of morphosyntactic evidence are provided for distinguishing compounds from nominal juxtapositions. A true compound exhibits none of the following three properties: 1) internal genitive marking, 2) ellipsis and 3) (multiple) modification. By contrast, nominal juxtapositions generally are characterized by the three properties stated above. This paper also shows that Mantauran exhibits a specific pattern in its classification of compounds. More specifically, it exhibits the attributive and subordinate types (Bisetto & Scalise 2005), while the coordinate type is not observed; most of subordinate compounds express a theme-location relation.