Using a habituation paradigm with a three-switch design, the present study investigated whether 20-month-old French-learning infants use noun and verb morphosyntactic cues to learn novel words in dynamic events differentially when both the agent and the action interpretations are possible. Of particular interest was whether infants' initial interpretation of novel nouns referring to novel animate objects in dynamic events includes not only the novel agents but also their actions. The following two contrastive hypotheses were specifically tested: (1) infants map novel verbs to the novel actions only and novel nouns to the novel agents only. Alternatively, (2) they map novel verbs to the novel actions only but novel nouns to both the novel agents and their actions. Infants watched dynamic events in which novel agents performed novel intransitive actions, while hearing novel words in a noun phrase or a verb sentence. When novel words were preceded by a pronoun "il", infants were able to map novel verbs to the actions but not to the agents. However, when novel words were preceded by a determiner "un", they mapped the novel nouns to both the agents and their actions. Two follow-up noun experiments showed that they mapped the novel nouns onto the agents and their actions, even when additional noun morphosyntactic cues were given. These findings demonstrate that 20-month-old infants are able to use noun and verb morphosyntactic cues to learn novel words in dynamic events differentially and provide some evidence to support that infants' initial representations of novel nouns referring to novel animate objects in dynamic events include both the agents and their actions.