This Festschrift volume in honor of Professor Alexander Karczmar is the outcome of a three-day symposium entitled "Neurobiology of Acetylcholine" held at Loyola University Medical Center from June 3 to 5, 1985. This volume serves two purposes. It expresses the respect and admiration of the contributors to Alex Karczmar, and it provides a forum for detailing recent advances in the cholinergic field which has attracted the undivided and untiring attention of Dr. Karczmar over some 40 years. During this period, the cholinergic system has grown from its infancy to become one of the most studied and understood transmitter systems today. Dr. Karczmar's interest in cholinergic system is appropriately reflected by the range of topics, molecular, cellular, developmental, behavioral and toxicological, that were discussed here. A detailed synopsis of Dr. Karczmar's research and his contributions to the field of cholinergic systems can be found in the following chapter by his close friend and colleague, Dr. George Koelle. We would like to take this opportunity to thank the enthusiastic responses of the participants making this Festschrift a memorable event.