How do children learn their first words? The field of language development has been polarized by responses to this question. Explanations range from accounts that emphasize the importance of cognitive heuristics in language acquisition, to those that highlight the role of "dumb attentional mechanisms" in word learning. This monograph offers an alternative to these accounts. A hybrid view of word-learning, called the emergentist coalition theory, combines cognitive constraints, social-pragmatic factors, and global attentional mechanisms to arrive at a balanced account of how children construct principles of word learning. In twelve experiments, with children ranging from 12 to 25 months of age, data are described that support the emergentist coalition theory.