This text explores the emergent construction of “unequal” populations in Latin-America, focusing on three national traditions: Argentina, Brazil and Mexico. It compares who has been named as unequal in educational research and under what categories, and treats this comparison as an indicator for understanding the phenomenon of educational inequalities in the region between 1960 and 1970. It is concluded that the rules used to enforce inclusion, equality and equity are, at the same time, standards and divisions that involve the construction of systems of reasoning that also simultaneously include and exclude.