ObjectiveThe purpose of this paper is to review and discuss the history of chiropractic vertebral subluxation theories between 1928 and 1949. DiscussionTheories during this period grew in complexity and developed in 4 primary ways: upper cervical models, reflex models, global models, and models based on the work of Speransky. Authors, theorists, and technique developers during this time included B. J. Palmer, R. J. Watkins, Galen Price, John Hurley, Hugh Logan, Major Bertrand DeJarnette, Richard Van Rumpt, Roy Ashton, Joseph Janse, Henri Gillet, James Firth, and J. R. Verner. At least 8 perspectives on chiropractic vertebral subluxation were advanced through research, modeling, and applied clinical methods. By understanding the complexity of this period and analyzing the research, the modern practitioner will be able to appreciate this era. The foundations of modern clinical practice and theoretical applications have roots in this period. ConclusionTheories during this period developed in levels of complexity, expanding existing models and clinical practice methods. The theories and research from this period had an effect on the chiropractic profession for the subsequent decades.