Recapitulating the three ages of urban ethnography born in Chicago a century ago, this book puts into historical and analytical perspective a controversy over the ethnography of the nexus of race, class, and morality in and around the black American ghetto in the age of triumphant neoliberalism, in order to draw from it positive lessons for the theory and practice of fieldwork. Thoughtless empiricism, acceptance of problematics prefabricated by ordinary and political common sense, confusion between folk and analytical categories, confinement to the immediate perimeter of interaction, bifurcating moralism: these are all traps that every ethnographer encounters sooner or later on her path and that only collective vigilance can hope to thwart.This epistemological return is an opportunity to pinpoint the danger of _ethnographism_, the tendency to want to describe, interpret, and explain a phenomenon based solely on the elements discerned through fieldwork, and to call for the correlative practice of an _enactive, structural, and historicized ethnography_ that sets out to embed the micro-actions observed in the interlocking series of nested social spaces that shape them and give them sense. Such an ethnography allows us to avoid falling into one or another of the five fallacies of participant observation: interactionism, inductivism, populism, presentism, and the hermeneutic drift. And to move beyond Clifford Geertz's "thick description" with the "thick construction" inspired by Pierre Bourdieu, whose mission is to construct scientifically the ordinary social construction of reality.