Children sometimes seem to expect words to have mutually exclusive meanings in certain contexts of early word learning. In 2 studies, 12- to 24-month-old children and their parents were videotaped as they engaged in conversations while playing with sets of toys (sea creatures, vehicles, doll clothing) in free-play, storytelling, and categorization contexts. In both studies, parents demonstrated a reliable preference to provide just 1 label for a given object. Importantly, parents' violations of this preference were usually accompanied by clarifying (or "bridging") information that either indicated the relation between the 2 labels or suggested that 1 of the labels was appropriate. Further, in some contexts, parents' tendency to use multiple labels and to provide bridging information for multiple labels was correlated with children's productive vocabulary. It is argued that these findings support a socio-pragmatic hypothesis about the origins of children's early beliefs about word meanings.