In recent times, the development of Western welfare states has been strongly influenced by regulatory and managerial approaches that embody what this special issue refers to as ‘governing by numbers’. This article delineates this development by using the example of the human service industry in Germany. The analysis is embedded in a macrosociological perspective on blurring boundaries between the capitalistic (market) economy and the welfare state, arguing that a certain kind of (instrumentalist) numeric rationalization has spilled over from the former to the latter and sets limits to what is named ‘human development rationality’ within the operational core of involved organizations. Drawing on case study evidence from four different areas, it is shown in which dimensions this movement takes shape and how it fosters the crowding-out of elements inherent to this rationality. However, due to the proliferation of ever more ‘perfectionist’ expectations concerning quality issues, this crowding out provokes various provisional organizational and institutional responses. While the latter make production processes more volatile overall, there is no end of history regarding the struggle between instrumental rationality and countervailing forces within contemporary welfare states.