The present paper focuses on pseudopartitive constructions headed by quantifier, collective, or container nouns (like a lot of senators, a group of students, a bottle of pills) followed by a singular or a plural verb. We compared these structures with superficially similar adnominal structures of the form NP1[−PL] prep NP2[PL] (e.g., the level of the lakes is/are) in Italian in an acceptability judgment study (Experiment 1), a forced-choice task (Experiment 2), and an eye tracking reading study (Experiment 3). Two major findings were consistent across all studies. First, verb agreement in pseudopartitives always patterned differently from controls. Second, albeit an overall preference for singular verbs was observed, a gradient difference emerged between adnominal controls and pseudopartitives, and among pseudopartitives headed by different nouns. We explain such variability in terms of the availability of a measure interpretation (e.g., pills in the measure of a bottle vs. a bottle containing pills) which is linked to the type of the pseudopartitive’s head noun. While in non-pseudopartitive adnominal structures only one parse is allowed by the grammar, in pseudopartitives a given head noun may admit or block a structural configuration in which the plural feature of the embedded constituent (e.g., of students, modifying a group) can determine the plurality of the subsequent verb. We conclude that verb agreement in pseudopartitives is a grammatical phenomenon and, as such, it refers to speakers’ grammatical competence and cannot be reduced to agreement attraction of the plural intervener.