What have been the role and the place of small enterprises in industrialized countries since the late 19th century? Are they a relic of the past, an area of innovation, or an opportunity for employment at a time of high unemployment? Political economy became a science in the late 18th century by demonstrating the benefits of mass production (Adam Smith’s theory of pin manufacturing). However, according to Rosa Luxemburg, an economy only made up of large enterprises has never existed and will never exist. This paper aims to analyze these questions through theories of the firm and of the entrepreneur. JEL codes: B30, 031, L25, L26