On which grounds have “Amerindians” been identified and counted on the American continent? This paper is based on censuses carried out between 2000 and 2001 in the United States, Mexico, and Bolivia. Describing some of the battles caused by the census of Indians, the authors emphasize their indissoluble links with politics and public policy. Basically, they suggest that categories such as ethnicity and culture—that seem to be great scientific strides—have transformed censuses for the worse as they introduce wrong classifications, back up preconceived opinions, and possibly give rise to conflicts.