In 4 experiments, we examined 16- and 20-month-old infants' understanding of proper names and count nouns. In each experiment, infants were taught a novel word modeled linguistically as either a proper name (e.g., "DAXY") or a count noun (e.g., "a DAXY") for a stuffed animal shown on a puppet stage. This animal was moved to a new location on the stage, and a second identical-looking animal was placed in the original animal's starting location. We then assessed infants' looking behavior in response to the word they had heard. At 20 months (Experiments 1 and 3), but not at 16 months (Experiments 2 and 4), infants were significantly more likely to look first at the original object in response to hearing the word in the proper name condition than in the count noun condition or in a baseline condition in which they heard no word. The results suggest that distinct and appropriate form-meaning links involving proper names and count nouns emerge in children's language between 16 and 20 months. (Contains 6 figures and 4 footnotes.)