This book contains a collection of current research in the development of speech perception and perceptual learning. The collection integrates research involving infants, young children, and adults, and explores systematically how adult perceptual abilities develop from early infant capabilities, focusing particularly on the nature of transitional stages and the constraints they place on theories of speech perception. The nine chapters in the book are: (1) "Developing Theories of Speech Perception: Constraints from Developmental Data" (Judith Goodman and others); (2) "Observations on Speech Perception, Its Development, and the Search for a Mechanism" (Joanne Miller and Peter Eimas); (3) "The Importance of Childhood to Language Acquisition: Evidence from American Sign Language" (Rachel Mayberry); (4) "Cross-Language Speech Perception: Developmental Change Does Not Involve Loss" (Janet Werker); (5) "Perceptual Learning of Nonnative Speech Contrasts: Implications for Theories of Speech Perception" (David Pisoni and others); (6) "The Emergence of Native-Language Phonological Influences in Infants: A Perceptual Assimilation Model" (Catherine Best); (7) "Infant Speech Perception and the Development of the Mental Lexicon" (Peter Jusczyk); (8) "Sentential Processes in Early Child Language: Evidence from the Perception and Production of Function Morphemes" (LouAnn Gerken); and (9) "Learning to Hear Speech as Spoken Language" (Howard Nusbaum and Judith Goodman). Each chapter includes references. (TJQ)