The cochlea is a spiral-shaped structure in the inner ear that is responsible for hearing. It converts sound vibrations into electrical signals and sends them to the brain with remarkable precision. Defects in the cellular or molecular components of the cochlea can lead to deafness and other hearing impairments. Written and edited by experts in the field, this collection from Cold Spring Harbor Perspectives in Medicine provides a comprehensive review of the complex molecular machinery that is responsible for cochlear function and describes recent advances in understanding and treating various forms of hearing loss. The contributors focus on the highly specialized cells that are critical for auditory transduction–the hair cells–and their unique molecular and biomechanical characteristics. They also consider the properties of other cochlear components, including the tectorial membrane, synaptic connections, and resident macrophages, as well as the development and evolution of the cochlea as a whole. Topics such as hair cell regeneration, otoacoustic emissions, and ototoxicity are also discussed. In addition, the authors examine the epidemiology and pathology of hearing loss and emerging therapeutic strategies (e.g., optical cochlear implants) for addressing it. This volume is therefore a valuable reference for cell biologists and neuroscientists interested in the biology of hearing, as well as physicianscientists seeking new approaches to alleviate hearing impairments.