Inoculation has an important place in the history of medicine: not only was it the first form of preventive medicine but its history spans the so-called eighteenth century 'medical revolution'. A study of the myriad of pamphlets, books and articles on the controversial practice casts new light on these fundamental changes in the medical profession and medical practice. Whereas historians have associated the abandonment of old humoural theories and individualised therapy in favour of standardised techniques with the emergence of new institutions in the second half of the century, inoculation suggests that changes began as early as the 1720s. Though inoculation was initially accompanied by a highly individualised preparation of diet and drugs, more routinised sequences of therapy appeared the 1740s and by the late 1760s all inoculated patients followed exactly the same preparative regimen. This in turn made possible the institutionalised provision of inoculation, first through the system of poor relief, later by dispensaries and charitable societies. In addition, debates over inoculation reveal the disintegration of the old professional order and the struggles of the physicians--whose authority was based in individualised practice--to retain their monopoly of inoculation and their status as authorities on the practice. By the 1770s, the intellectual and professional leadership of the profession passed to a new generation of practitioners. The thesis ends with an assessment of the impact of inoculation on population growth and finds that it was not widely practiced and had, at best, a marginal effect on mortality.