It is generally assumed that The Vampyre was published against John Polidori's will. This article brings evidence to support that he played, in fact, an active role in the publication of his tale, perhaps as a response to Frankenstein. In particular, by making use of the tools of textual criticism, it demonstrates how the ‘Extract of a Letter from Geneva’ accompanying The Vampyre in The New Monthly Magazine and in volume editions could not be written without having access to Polidori's Diary. Furthermore, it hypothesizes that the composition of The Vampyre, traditionally located in Geneva in the course of summer 1816, can be postdated to 1818, opening up new possibilities for reading the tale in the context of the relationship between Polidori, Byron, and the Shelleys.