Industrial citizenship developed as a way to socially regulate markets in democratic societies. However, EU regulation and one form of labour mobility unique to the European Union, namely posted work, undermines national industrial citizenship through constitutionalizing markets. This chapter examines the contradictions between industrial and market citizenship concepts, and traces their implications in practice. It focuses on how posted work introducies into the German industrial relations system a class of workers with tenuous relations to the system’s regulatory jurisdiction. This undermines industrial citizenship in Germany. Use of posting avoids contesting the validity of labour rights and industrial citizenship concepts directly, but instead asserts that specific workers under exceptional circumstances are outside realm of application of those concepts. Based on interviews of posted workers, trade unionists, managers, and policy makers we examine the contradictions between industrial and market citizenship concepts, and trace their implications in practice. Findings show that the dominance of market concepts in the EU regulation of posted work circumvents and undermines Germany’s industrial citizenship institutions.