THE CARE OF STRANGERS The Rise of America's Hospital System By Charles E. Rosenberg Basic Books. 437 pp. $22.95

Few institutions are more central to our lives than the hospital. Most of us were born in hospitals; many of us will die in them. And quite apart from their key role in life's major passages, hospitals are ubiquitous. Practically every community has one, and in major urban centers they are truly imposing edifices of concrete, glass and steel. Most of us enter them with a sense of awe, unable to comprehend the vocabulary and the technology we encounter there. Yet we also approach them with a profound sense of hope, because we admire the knowledge and respect the skill of the physicians who preside over these modern-day cathedrals of science.

Despite their importance, however, hospitals have not been studied much by historians. With a few noteworthy exceptions, most scholars have focused on individual institutions, bestowing praise on their farsighted trustees and hard-working staffs. As a genre, such studies do not help us understand how America's hospital system has been shaped by our values, or how hospitals have changed.

Charles E. Rosenberg's long-awaited "The Care of Strangers: The Rise of America's Hospital System" marks a milestone in our understanding of the hospital as a social institution. The task he sets for himself (which he accomplishes admirably) is to examine the complex dialectic between the hospital and society, or, in his words, to use the hospital to reflect "in microcosm the history of the larger society."

Rosenberg, who teaches the history of medicine at the University of Pennsylvania, traces the rise of the hospital from 1800 to 1920. In Thomas Jefferson's day, there were only two hospitals in the United States, one in Philadelphia, the other in New York. And despite all the rhetoric about equality, America in 1800 was a deferential society, with sharp social boundaries separating the classes. Middle- or upper-class Americans did not enter hospitals when they became ill. Instead, they received medical care in the comfort and privacy of their homes.

Hospitals were for a different class of people -- the worthy poor. (The unworthy poor wound up in almshouses.) As a group, the worthy poor included visiting seamen of good character, local workmen with solid reputations, virtuous widows and the like. Hospitals were established for their care, and they were in every sense of the word "benevolent" institutions whose internal relationships were ordered by the same notions of social deference and patriarchy that governed the rest of society. Hospital admissions were determined by a dual test of character and means, not by medical diagnoses. And the decisions rested with the hospital's trustees, who accepted this duty as an exercise in Christian stewardship. Physicians had very little authority in the hospital's day-to-day affairs.

By 1920, America boasted nearly 5,000 hospitals. Within these institutions, both the wielders of power and the social backgrounds of the patients had changed dramatically. The trustees had receded into largely honorific roles, and real authority had shifted to the medical profession. Admissions were based on medical diagnoses, not on character assessments. Moreover, the hospital's patients now included members of the upper class and middle class, as well as the poor.

Explaining changes of this magnitude is no mean feat, but Rosenberg is more than equal to the challenge. Drawing upon profound historical learning and an acute understanding of sociological theory, he identifies the actors, forces and social changes that moved the hospital from the fringes of medicine to its center stage. Among the many topics that fall under his deft scrutiny are the role of urban-based medical elites, reforms in medical education, the rise of scientific medicine, the development of nursing as a medical profession, the rising costs of medical care, and the public's growing admiration of physicians and deference to medical authority.

For the last 25 years, historians and sociologists of medicine have grown accustomed to having their intellectual sights raised a notch by Charles Rosenberg. "The Care of Strangers" shows why. It should be read by anyone who wants a sophisticated analysis of the forces that have shaped the modern hospital system.

The reviewer, who teaches history at the University of Houston, is at work on a biography of Alfred C. Kinsey.