Using an observational task followed by an experimental task with an Intermodal Preferential Looking Paradigm, we examined the effect of input on children's acquisition of class extension rules by investigating the relationship between the amount of polysemous noun-verb pairs in French-speaking 2-year-olds' input and both their spontaneous "production" of these words and their "comprehension" of novel instances of these words. Study 1 demonstrated that the number of words children used cross-categorically was related to the number of words their mothers used cross-categorically. Children also used object-denoting words cross-categorically more often than nonobject- and action-denoting words. Study 2 demonstrated that only children whose mothers frequently used noun-verb pairs cross-categorically were able to understand the cross-categorical use of the novel object-denoting words in the experimental task. This suggests that semantic and distributional cues associated with object-denoting noun-verb pairs in the input play an important role in children's acquisition of class extension rules.