Learning new words involves decoding both how a word fits the current situation and how it could be used in new situations. Three studies explore how two types of cues--sentence structure and the availability of multiple instances--affect children's extensions of nouns and verbs. In each study, 2.5-year-olds heard nouns, verbs, or no new word while seeing the experimenter use a novel object to perform an action; at test, they were asked to extend the word. In Study 1, children hearing nouns in simple sentences used object shape as the basis for extension even though, during the learning phase, they saw multiple objects in motion; children in the other conditions responded randomly. Study 2 shows that by changing the type of sentences used in the noun and verb conditions, not only is the "shape bias" disrupted but children are successful in extending new verbs. In a final study, access to multiple examples was replaced by a direct teaching context and produced findings similar to those in Study 2. An implication of this result is that seeing multiple examples can be as effective as receiving direct instruction from an adult. Overall, the set of results suggests the mix of cues available during learning influences noun and verb extensions differently. The findings are important for understanding how the ability to extend words emerges in complex contexts. (Contains 3 tables, 1 figure and 3 footnotes.)