This paper considers the syntactic and semantic properties of two vocabulary items in Tagalog, ang and ng. It is shown that although ang and ng appear to encode definiteness (via familiarity), they are in fact unmarked for definiteness, being compatible with both familiar and novel readings. Crucial data from modification by weak quantifiers are presented in favour of this description. The default interpretation of ang and ng as familiar and novel, respectively, arises due to their syntactic position (subject versus object). Given that ang and ng mark case, it is argued that they are case markers in K° and not determiners.