This paper examines the diverse responses of the German states to the Code Napoleon at the beginning of the nineteenth century. These states differed both in the extent to which they adopted the Code, and the extent to which they retained the Code after Napoleon's influence waned. In order to identify the causes of adoption and retention of the Code, we use fuzzy-set qualitative comparative analysis (fsQCA). This method is now well established in comparative research in the social sciences but has been little used in comparative legal analysis. We find the following to be among the conditions relevant to the reception of the Code: territorial diversity, control by Napoleon, central state institutions, a feudal economy and society, liberal (enlightented absolutist) rule, nativism among the governing elites and popular anti-French sentiment. The paper also serves to demonstrate the potential of fsQCA as a method for comparative lawyers.