Analyzing twenty-two examples of fan fiction, Chapter 3 uncovers the unwritten customary norms that governed the production and dissemination of these works. After defining customary norms as an alternative to formal law and briefly accounting for their potential origin, this chapter analyzes each norm in detail. In all, five rules, or customary norms, governed the production of fan fiction in the eighteenth century. Together, they amounted to a customary intellectual property regime comprising rights, trespass norms, exceptions, and enforcement mechanisms. This chapter then examines an exception to the rules for publishers who held the right to publish sequels and continuations. Finally, it focuses on Nicolai’s Joys of Young Werther and Schiller’s Geisterseher as examples of the effectiveness of these mechanisms, showing how they prevented egregious departures from the customary norms.