Outlining an approach to the development of communicative behavior from early infancy to the onset of single word utterances, Nobuo Masataka's research is rooted in ethology and dynamic action theory. He argues that expressive and communicative actions are organized as a complex and cooperative system with other elements of the infant's physiology, behavior and social environments. This book offers new insights into the precursors of speech and will be of interest to researchers and students of psychology, linguistics and animal behavior biology.