One of the main users of the popular libraries was the working class, which found in the books the opportunity to go to an education previously inaccessible. Their literacy was thus a key factor in the configuration of self-awareness and in the struggle for their rights as a class. Thus, this article constitutes an approximation to the function of the book and reading among the workers of socialist tradition from the study of the library of the House of the People from Madrid in the first third of the twentieth century. History of Written Culture, History of Education, History of book and reading, History of libraries, socialist working class, workers Libraries, Library of the House of the People from Madrid.