Previous research on infant perception of speech has shown that infants prefer their mother's voice over the voice of an unfamiliar female. Additionally, infants show a preference for the type of speech that is normally directed towards infants, known as infant-directed (10) speech. The linguistic and prosodic features of 10 speech are typically exaggerated in comparison to speech that is used amongst adults (adult-directed or AD speech). Most previous studies investigating infant preference for 10 speech have used the voice of a woman unfamiliar to the infants tested. The only study to use the maternal voice in testing 10 speech preferences employed 9 and 16-month-old infants. Knowledge of how the maternal voice impacts speech preferences in younger infants is unknown. The current study examined 1-month-old infants' preference for maternal 10 speech, when the alternative was maternal AD speech. Samples of individual mothers' 10 and AD speech were obtained during home visits, and selected utterances were subsequently presented to the infants in a visually based preference procedure. One month-olds showed no preference for either maternal speech type, although acoustic analyses showed that the 10 speech did differ significantly from the AD speech on all prosodic parameters examined. This lack of preference for maternal ID speech in young infants is discussed in a developmental model that depends on experience with maternal speech from prenatal to postnatal life with regard to the formation of infant speech preferences. / Master of Science