In the course of the long 18th century, medical theory and theories underwent profound changes. These in turn reflected discontinuities and often conflicting assumptions and premises, engendering divergent concepts of physiology and pathology. However, most theoretical considerations were only very inconsistently and partially reflected in therapeutic practice, which continued to be governed by experience with traditional and known medicinals and by patient expectations regarding provider practices. Additional factors in therapeutic decision making were economic considerations and preferences for particular therapies in certain social and religious networks. The present volume deals with some aspects of this complex relationship between medical theory and therapeutic practice, using a transatlantic perspective. Individual essays reflect the current state of historical research in Germany, the US and Great Britain.