This text was originally published by David S. Parker in 1998 as an introduction to the book The Idea of the Middle Class: White-Collar Workers and Peruvian Society, 1900-1950, published by Penn State University Press. In the book, the author reflects on the union organization of private employees in Lima (Peru) and the origin of the 1924 law that established a legal distinction between empleado (white-collar employee) and obrero (blue-collar worker). Both the “constructivist” school and the linguistic turn argue that social classes are abstractions, inventions of the collective imaginary, that is, ideas that compete in an ideological market. Among the infinite ways of conceptualizing society, only a few images and discourses become common sense, influencing the formation of identities and inspiring laws and public policies. This text affirms and characterizes that the formation of the middle class concept in Peru is due to ideological, discursive and political processes.