The morphological system of cardinal numerals in Modern Hebrew is currently undergoing rapid changes, enabling linguists to unravel the forces shaping the change as it takes place. In the free forms, gender marking on numerals is neutralized by collapsing both masculine and feminine forms into one paradigm, the feminine paradigm. In the bound (definite) forms, an opposite direction is attested, in that at least for some numerals, the masculine forms become more prevalent. The study reported here aims to determine whether the factor determining the change is prosodic or functional in nature, by eliciting production and grammaticality judgments of noun phrases containing bound numerals from five different age groups of native speakers. The results suggest that prosody plays a role in shaping the change, as forms with penultimate stress are favored over those with ultimate stress. In addition, processes of production and processes of grammaticality judgments seem to be subject to different kinds of constraints. This state of affairs indicates that the tension between the tendencies toward simplification on the one hand and maximal distinctness on the other occurs at the morphological level as well.