The major targets of number agreement in English are pronouns and verbs. To examine the factors that control pronoun number and to test pronouns against a psycholinguistic account of how verb number arises during language production, we varied the meaningful and grammatical number properties of agreement controllers and examined the impact of these variations on the number values of pronouns in sentence completion tasks. The number values taken by pronouns were systematically compared to the number values taken by verbs over the same range of conditions. The findings supported the hypothesis that pronouns acquire number lexically while verbs acquire it syntactically, with differently weighted contributions from number meaning. In contrast, pronouns were just as vulnerable as verbs to the effects of number attraction, suggesting that the mechanisms responsible for reconciling number features within utterances work in the same way for pronouns as for verbs. The results imply that the transformation of notional number into linguistic number (what we call marking) may be dissociable from the implementation of number agreement during language production (what we call morphing).