The communities of the Western Sephardic Diaspora were founded in the 16th and 17th centuries by New Christians from Iberia who returned to Judaism that had been abandoned by their ancestors in the late Middle Ages. This project will concentrate on the changes in the religious conceptions and behavior as well as the cultural patterns of the communities of Amsterdam, Hamburg, Leghorn, London, and Bordeaux. We will analyze the vigorous activity of their leaders to set the boundaries of their new religious identity in comparison to the policy of several Christian “communities of belief,” which went into exile following religious persecution in their homelands. We will also examine the changes in the attitude toward Judaism during the 17th century in certain segments of the Sephardic Diaspora: rather than a normative system covering every area of life, Judaism came to be seen as a system of faith restricted to the religious sphere. We will seek to explain the extent to which this significant change influenced their institutions and social behaviour. This study will provide us with better understanding of the place of the Jews in European society. At the same time, we will subject a central series of concepts in the historiographical discourse of the Early Modern Period to critical analysis: confessionalization, disciplinary revolution, civilizing process, affective individualism, etc. This phase of the research will be based on qualitative and quantitative analysis of many hundreds of documents, texts and the material remains of these communities. Using sociological and anthropological models, we will analyze ceremonies and rituals described at length in the sources, the social and cultural meaning of the architecture of the Sephardic synagogues of that time, and of other visual symbols.