An ethnographer's safari into the black-and-white world of Ultra-Orthodox Jews. To the subjects of this rare study, Heilman, an adherent of Modern-Orthodox Judaism, was both an insider and an outsider, and the resulting combination of partial access yet professional distance gives the author's voice a dynamism lacking in many sociological studies of comparable subcultures. Heilman (Sociology/CUNY) takes us inside the ritual baths, study halls, synagogues, kitchens, and bedrooms of these half-a-million singular denizens of Jerusalem and Brooklyn. While it is tempting to think of these pious black-hatted or scarved Jews as being somewhat medieval, Heilman explains how they are very much a modern and post-Holocaust reactionary phenomenon. The community is said to be reacting to the collapse of family values in general and to strong Jewish identification in particular. Traditionalism is so entrenched within members of this group that they perceive their own sages and community leaders to be inferior to those of previous generations. Nonetheless, to Ultra-Orthodox Jews a man's lifetime of devotion to sacred texts is considered to be an act of ``defense'' no less vital than any soldier's, and a rare divorce suit might allege that a husband was lax in his God-fearing or study habits. Heilman adds enough local color to allow us to differentiate between the dozens of varieties of ``haredim'' (God-fearers), but his study reinforces the perception that his subjects live in a simply perceived world of theological givens.