This thesis is a critical edition of William Sampson's mid-seventeenth-century play, The Vow Breaker, or The Fair Maid of Clifton, edited according to the guidelines set down by the Revels Plays Series. The Introduction is divided into ten sections: William Sampson; performance; synopsis; the siege of Leith; navigation of the Trent; other seventeenth-century vow breakers; the significance of The Fair Maid of Clifton; genre; the 1636 text; Hans Wallrath. In addition, there is a full textual collation and details of editorial procedures. The play itself is presented in a fully modernised version. There is a full Commentary with index, and a bibliography. In the Appendix there is a facsimile of the Bodleian copy of The Vow Breaker and a map suggesting Sampson's connection with the counties of Nottingham and Derby. This is the first modem edition of The Vow Breaker and is supported by a full Commentary. The Introduction supplements that of Hans Wallrath of 1914 and brings together in one place all the other information that I have been able to find about the play and its contexts. My thesis makes this little-known play accessible to modem readers and enables some, at least, of its original meanings and resonances to be recovered. In addition, I have produced a text that might be usable to anyone who wished to stage a performance.