The molecular genetics of the cholinergic system including both muscarinic and nicotinic acetylcholine receptors, cholinesterases, acetylcholine synthesis and release have provided significant insights into potential targeting for pharmacological intervention. Cholinergic drugs are being used or evaluated for the treatment of diseases. Thus, this volume aims to broaden our understanding of the current state of cholinergic mechanisms to enable implementation of novel approaches for the development of more effective treatments.