When children use objects like adults, are they simply tracking regularities in others' object use, or are they demonstrating a normatively defined awareness that there are right and wrong ways to act? This study provides the first evidence for the latter possibility. Young 2- and 3-year-olds (n = 32) learned functions of 6 artifacts, both familiar and novel. A puppet subsequently used the artifacts, sometimes in atypical ways, and children's spontaneous reactions were coded. Children responded normatively to non-designed uses (e.g., protesting, tattling), although the effect was stronger among older children. Reactions were identical for novel and familiar items, underscoring how rapidly tool-function mappings are formed. Results depict toddlers as already sensitive to the uniquely human, normative nature of tool use. (Contains 2 tables.)