The inner ear originates from an ectodermal thickening, the otic placode, which lies adjacent to the developing hindbrain. Complex interactions between regulatory signaling molecules guide development of the simple otic placode into the elaborate, multifunctional organs of hearing and balance. This book delves into recent research in the field, focusing on successive stages of inner ear development and how they are influenced by the coordinate activity of signaling molecules. This book begins with an overview of the evolutionary adaptation of the organ of Corti (organ of hearing) and the molecular signals that characterize ancestral development of the inner ear. Following this, the topics addressed include the complex signaling interactions underlying induction of the otic placode, key molecular mediators influencing inner ear development and patterning, genetic signaling of the vestibular (balance) system and clinical correlations to human balance disorders, commitment to auditory hair cell fate, and reliance of the inner ear on retinoic acid, a biologically-active derivative of vitamin A, for appropriate development. This timely and comprehensive book provides an excellent resource for researchers, clinician-scientists and students alike.