This book explores several subtypes of muscarinic receptors that modulate smooth muscle activity. Main topics include a classification of muscarinic receptors, biochemical responses that occur in smooth muscle, the role of muscarinic receptors in the function of gastrointestinal and genitourinary smooth muscle, and prejunctional muscarinic receptors in smooth muscle. Discussions cover the current state of research and are intended to generate further research into the design of novel therapeutics for disorders of smooth muscle function.