In recent years there has been increasing interest and, subsequently, active research in neuropeptides. These neuroactive molecules coordinate, integrate, and regulate physiological processes in all organisms, throughout all phases of development. Acting as neurohormones, neurotransmitters, and/or neuromodulators, they maintain physiological homeostasis and influence important behavioral patterns. This textbook is the first to bring together and synthesize the neuropeptide research of the past decade in such a comprehensive, scholarly manner.