The speech commonly addressed to infants (infant-directed speech or IDS) is believed to have multiple functions, including communication of emotion and highlighting linguistic aspects of speech. However, these two functions are most often studied separately so that the influence of emotional prosody (the changes in intonation and vocal quality that relate to emotion) on linguistic processing in infants has rarely been addressed. Given that language learning during infancy occurs in the context of natural infant-caretaker exchanges that most certainly include emotion communication and co-regulation, it is important to integrate the concepts of emotional communication and linguistic communication in studying language learning. This study examined the influence of both positive (happy) and negative (sad) face+voice contexts on word recognition in 11-to-13-month-old infants. It was hypothesized that infants would learn and subsequently recognize words when they were delivered in a happy context, but will experience more difficulty in learning and/or recognition of the same words when delivered in a sad context. The general pattern of results confirmed these predictions in that after habituating to sentences containing a specific target nonsense word, infants in the Happy Condition recovered their attention to the same sentences with a novel target word. In contrast, infants in the Sad Condition showed no significant recovery to a change in target words. These results contribute to our understanding of how emotional tone can facilitate and/or attenuate attention in older infants as they engage in language learning with their caretakers. / Ph. D.