Mandarin Chinese allows pervasive ellipsis of noun arguments (NPs) in discourse, which casts doubt concerning child learners' use of syntax in verb learning. This study investigated whether Mandarin learning children would nonetheless extend verb meanings based on the number of NPs in sentences. Forty-one Mandarin-speaking two- and three-year-olds enacted sentences with familiar motion verbs. The presence of an extra postverbal NP led the toddlers to extend causative meanings to intransitive verbs, and the absence of a postverbal NP led them to extend noncausative meanings to transitive verbs. The effects of adding or subtracting an NP were statistically indistinguishable. Thus, the number of NPs in a sentence appears to play a role in verb learning in Mandarin Chinese.