Sensory hair cells in the inner ear and vestibular system convert mechanical stimuli, sound, and motion into neural activity that is responsible for the sensations of hearing, motion, and head position. In mammals, the loss of hair cells from acoustic over-stimulation, ototoxic drugs and aging is irreversible, leading to a permanent loss of function. However, it is now clear that hair cells in other vertebrates are capable of regenerating and recovering partial or complete function. This book provides a comprehensive survey of what is currently known about the regeneration, repair, and protection of sensory hair cells and the subsequent recovery of function in the auditory and vestibular systems. The editors and authors provide graduate students, clinicians, and scientists in the biological basis of hair cells and with an understanding of the factors that contribute to their regeneration and repair.