 Throughout its history, the American medical school, like the rest of the country's system of higher education, had been shaped by social, economic, and political developments in the larger society. Thus, it was hardly a surprise that many of the pressures experienced by academic health centers in the 0000s and 0000s arose from outside events. Yet, academic health centers encountered additional dilemmas that could not so clearly be related to external pressures. A number of traditional challenges to medical education grew more intense: the problem of teaching bedside medicine as biomedical research became increasingly molecular, the perpetual difficulty of achieving a suitable institutional balance between teaching and research, and the ongoing dilemmas of residency and fellowship training. These frustrating problems arose mainly from the evolution of medical knowledge and the institutional development of academic health centers rather than from the challenges imposed by a hostile external environment.