Osteopathy is a pseudoscientific system of alternative medicine that emphasizes physical manipulation of the body's muscle tissue and bones. In most countries, practitioners of osteopathy are not medically trained and are referred to as osteopaths. It is distinct from osteopathic medicine, which is a branch of the medical profession in the United States.

Osteopathic manipulation is the core set of techniques in osteopathy. Parts of osteopathy, such as craniosacral therapy, have been described by Quackwatch as having no therapeutic value and have been labeled by them as pseudoscience and quackery. The techniques are based on an ideology created by Andrew Taylor Still (1828–1917) which posits the existence of a "myofascial continuity"—a tissue layer that "links every part of the body with every other part". Osteopaths attempt to diagnose and treat what was originally called "the osteopathic lesion", but which is now named "somatic dysfunction", by manipulating a person's bones and muscles. Osteopathic Manipulative Treatment (OMT) techniques are most commonly used to treat back pain and other musculoskeletal issues.^{[non-primary source needed]}

Osteopathic manipulation is still included in the curricula of osteopathic physicians or Doctors of Osteopathic Medicine (DO) training in the US. The Doctor of Osteopathic Medicine degree, however, became a medical degree and is no longer a degree of non-medical osteopathy.

The practice of osteopathy (from Ancient Greek ὀστέον (ostéon) 'bone' and πάθος (páthos) 'pain, suffering') began in the United States in 1874. The profession was founded by Andrew Taylor Still, a 19th-century American physician (MD), Civil War surgeon, and Kansas territorial and state legislator. He lived near Baldwin City, Kansas, during the American Civil War and it was there that he founded the practice of osteopathy. Still claimed that human illness was rooted in problems with the musculoskeletal system, and that osteopathic manipulations could solve these problems by harnessing the body's own self-repairing potential. Still's patients were forbidden from treatment by conventional medicine, as well as from other practices such as drinking alcohol. These practices derive from the belief, common in the early 19th century among proponents of alternative medicine, that the body's natural state tends toward health and inherently contains the capacity to battle any illness. This was opposed to orthodox practitioners, who held that intervention by a physician was necessary to restore health in the patient. Still established the basis for osteopathy, and the division between alternative medicine and traditional medicine had already been a major conflict for decades.

The foundations of this divergence may be traced back to the mid-18th century when advances in physiology began to localize the causes and nature of diseases to specific organs and tissues. Doctors began shifting their focus from the patient to the internal state of the body, resulting in an issue labeled as the problem of the "vanishing patient". A stronger movement towards experimental and scientific medicine was then developed. In the perspective of the DO physicians, the sympathy and holism that were integral to medicine in the past were left behind. Heroic medicine became the convention for treating patients, with aggressive practices like bloodletting and prescribing chemicals such as mercury, becoming the forefront in therapeutics. Alternative medicine had its beginnings in the early 19th century, when gentler practices in comparison to heroic medicine began to emerge. As each side sought to defend its practice, a schism began to present itself in the medical marketplace, with both practitioners attempting to discredit the other. The osteopathic physicians—those who are now referred to as DOs—argued that the non-osteopathic physicians had an overly mechanistic approach to treating patients, treated the symptoms of disease instead of the original causes, and were blind to the harm they were causing their patients. Other practitioners had a similar argument, labeling osteopathic medicine as unfounded, passive, and dangerous to a disease-afflicted patient. This was the medical environment that pervaded throughout the 19th century, and the setting Still entered when he began developing his idea of osteopathy.

After experiencing the loss of his wife and three daughters to spinal meningitis and noting that the current orthodox medical system could not save them, Still may have been prompted to shape his reformist attitudes towards conventional medicine. Still set out to reform the orthodox medical scene and establish a practice that did not so readily resort to drugs, purgatives, and harshly invasive therapeutics to treat a person suffering from ailment, similar to the mindset of the irregulars in the early 19th century. Thought to have been influenced by spiritualist figures such as Andrew Jackson Davis and ideas of magnetic and electrical healing, Still began practicing manipulative procedures that intended to restore harmony in the body. Over the course of the next twenty five years, Still attracted support for his medical philosophy that disapproved of orthodox medicine, and shaped his philosophy for osteopathy. Components included the idea that structure and function are interrelated and the importance of each piece of the body in the harmonious function of its whole.

Still sought to establish a new medical school that could produce physicians trained under this philosophy, and be prepared to compete against the orthodox physicians. He established the American School of Osteopathy on 20 May 1892, in Kirksville, Missouri, with twenty-one students in the first class. Still described the foundations of osteopathy in his book "The Philosophy and Mechanical Principles of Osteopathy" in 1892. He named his new school of medicine "osteopathy", reasoning that "the bone, osteon, was the starting point from which [he] was to ascertain the cause of pathological conditions". He would eventually claim that he could "shake a child and stop scarlet fever, croup, diphtheria, and cure whooping cough in three days by a wring of its neck."

When the state of Missouri granted the right to award the MD degree, he remained dissatisfied with the limitations of conventional medicine and instead chose to retain the distinction of the DO degree. In the early 20th century, osteopaths across the United States sought to establish law that would legitimize their medical degree to the standard of the modern medic. The processes were arduous, and not without conflict. In some states, it took years for the bills to be passed. Osteopaths were often ridiculed and in some cases arrested, but in each state, osteopaths managed to achieve the legal acknowledgement and action they set out to pursue. In 1898 the American Institute of Osteopathy started the Journal of Osteopathy and by that time four states recognized osteopathy as a profession.