Chiropractic is a large and well-established health care profession in the United States. In this overview, we briefly examine the development of chiropractic from humble and contentious beginnings to its current state at the crossroads of alternative and mainstream medicine. Chiropractic has taken on many of the attributes of an established profession, improving its educational and licensing systems and substantially increasing its market share in the past two decades. The public increasingly uses chiropractic largely for spinal pain syndromes and appears to be highly satisfied with the results. Of all the so-called alternative professions, chiropractic has made the largest inroads into private and public health care financing systems and is increasingly viewed as an effective specialty by many in the medical profession. Much of the positive evolution of chiropractic can be ascribed to a quarter century-long research effort focused on the core chiropractic procedure of spinal manipulation. This effort has helped bring spinal manipulation out of the investigational category to become one of the most studied forms of conservative treatment for spinal pain. Chiropractic theory is still controversial, but recent expansion in federal support of chiropractic research bodes well for further scientific development. The medical establishment has not yet fully accepted chiropractic as a mainstream form of care. The next decade should determine whether chiropractic maintains the trappings of an alternative health care profession or becomes fully integrated into all health care systems.