The possessive dative construction has been widely adopted as an unaccusativity diagnostic (Borer and Grodzinsky 1986). Gafter (2014) casts doubt on the relevance of unaccusativity to the acceptability of the construction. We conducted a series of acceptability judgment experiments to investigate the validity of the possessive dative construction as an unaccusativity diagnostic, controlling for possible confounds such as animacy, definiteness, plausibility, lexical choice, type of possession, and context salience. The experiments revealed that possessive datives are significantly more acceptable with unaccusative verbs than with unergatives, including reflexive and emission verbs. We conclude that unaccusatives, but not unergatives, are grammatical in the construction, and we defend a structural account of the data.