This chapter examines the relationship between Percy Shelley and Mary Wollstonecraft Shelley. It follows them through a wide range of domestic settings in England, Switzerland, and Italy and emphasises their collaborative literary relationship, discussing both Mary Wollstonecraft Shelley’s Frankenstein, conceived during the inclement summer of 1816 on the shores of Lake Geneva, their jointly authored History of a Six Weeks’ Tour, and several of Percy Shelley’s poems, including Epipsychidion and The Cenci. The chapter discusses Mary Wollstonecraft Shelley’s essential role in editing and transmitting Percy Shelley’s works to literary history after the poet’s death.