At a time of growing interest in integrative approaches to health and care, this article examines, from a historical perspective, the factors underlying the global popularity of so-called complementary and alternative medicines (CAM). Focusing on the multiple and changing meanings of the concepts used with reference to CAM since the nineteenth century, it emphasizes the agency of CAM practitioners' and calls into question a linear progression from outright exclusion to gradual inclusion into mainstream health care systems. This analysis concludes that biomedicine and "other" medical systems have mutually defined each other in a process of co-production that has had a significant impact on the medicalization of contemporary societies from North America to East Asia.