This book, based on new research in the Spanish archives, is the first full-length account of the activities of the "linajudos," genealogists whose occupation was to scrutinize ancestries and to extort money from candidates for offices and honors who, in sixteenth- and seventeenth-century Spain, had to prove that they were not of "converso" (that is, Jewish) descent. In Seville many of the patrician families that dominated the transatlantic trade and governed the city in this period had intermarried with the conversos or were themselves of similar origin. This book views the "linajudo" phenomenon as part of the wider problem of the assimilation of the "conversos" into sixteenth- and seventeenth-century Spanish society.