As first remarked by Charles Darwin (1877), very young children frequently have difficulty when naming or choosing colors. To investigate the cause of this difficulty, we have tested preschoolers (mean age = 4.1) for hue discrimination and hue memory and compared their results with those of preadolescents (mean age = 9.6) and young adults (mean age = 25.8). The tests were designed to minimize the influence of verbal coding on the results. We find that preschoolers are as good as the two older groups in hue discrimination. However, in visual hue memory, they are significantly poorer. The 3-fold increased errors they make, relative to preadolescents and young adults, may be related to the development of visual hue categories and the integration of verbal and visual processes. However, such errors cannot explain why young children often experience extreme difficulty in color naming.