Research in diachronic linguistics has shown that homonyms are often dispreferred in language. This study proposes that this trend is mirrored in the difficulties that children encounter in mapping homonyms. Two experiments are presented in support of this proposition. In Experiment 1, 16 preschool children (mean age = 4;6) are shown to perform quite well on tasks requiring them to assign novel meanings to nonsense words. They perform poorly, however, on tasks requiring them to assign a different, unrelated meaning to a known word. Experiment 2 (N = 18, mean age = 4;5) shows that preschoolers' performance on this task, however, improves when a known word appears in a syntactic frame that is not appropriate for the word (as when a verb appears in a noun syntactic frame), thereby providing a strong indication that a new meaning is appropriate. (Contains 1 footnote.)