The developmental process of audiovisual speech perception was examined in this experiment using the McGurk paradigm (McGurk & MacDonald, 1976), in which a visual recording of a person saying a particular syllable is synchronized with the auditory presentation of another syllable. Previous studies have shown that audiovisual speech perception in adults and older children is very influenced by the visual speech information but children under five are influenced by the auditory input almost exclusively (McGurk & MacDonald, 1976; Massaro, 1984; and Massaro, Thompson, Barron, & Laren, 1986). In this investigation 46 children aged between 4:7 and 12:4, and 15 adults were presented with conflicting audiovisual syllables made according to the McGurk paradigm. The results indicated that the influence of auditory information decreased with age, while the influence of visual information increased with age. In addition, an adult-like response pattern was observed in only half of the children in the oldest child subject group (10-12 years old) suggesting that the integration of auditory and visual speech information continues to develop beyond the age of twelve.