This training study investigates how children learn to refer to things unambiguously. Two hundred twenty-four children aged 2.6, 3.6, and 4.6 years were pre- and post-tested for their ability to request stickers from a dense array. Between test sessions, children were assigned to a training condition in which they (a) asked for stickers from an adult, (b) responded to an adult's requests for stickers, (c) observed 1 adult ask another for stickers, or (d) heard model descriptions of stickers. All conditions yielded improvements in referring strategies, with condition (a) being most effective. Four-year-olds additionally demonstrated learning effects in a transfer task. These results suggest that young children's communication skills develop best in response to feedback about their own attempts at reference. [This research was supported by the Max Planck Institution for Evolutionary Anthropology, Leipzig, Germany.]