Recently a unique time series of the self-employment rate in the period 1899-1997 distinguishing three major sectors of industry was constructed for the Netherlands. It shows a continuous decline until the early 1980s and a revival thereafter. The role of changes in sectoral composition versus within-sector trends in explaining this development of self-employment was investigated through a shift-share analysis of these data. Overall, the evidence rejects a prime role of sector shifts. On the contrary, a deeply rooted process of upscaling followed by historically anomalous downscaling in almost all sectors of industry is the major proximate cause. This conclusion calls for a continued search for ultimate causes within the domains of technology, economics, institutions and culture.