Publisher Summary This chapter describes autonomic development in sequence, from embryonic neural crest induction to transsynaptic regulation in postnatal ganglia, to illustrate the variety of influences affecting transmitter phenotypic expression. The peripheral autonomic system arises from the neural crest, a transient embryonic structure that develops from the neural plate, neural folds, and neural tube. The mechanisms underlying the derivation of neural crest from neural tube are unknown, although it has been suggested that lateral sectors of the archenteron roof induce crest formation. Major pathways of neuronal differentiation of crest lead to development of sensory and autonomic neurons. In turn, autonomic neurons may utilize a variety of transmitters, including acetylcholine and norepinephrine. Increasing evidence indicates that cellular interactions play a pivotal role in transmitter choice. In vivo, tissue culture, and cell culture experiments are reviewed to analyze the manner in which heterogeneous cell populations interact with the environmental signals to define transmitter phenotypes. A number of recent reviews dealing with this subject are recommended.