One of the biggest hurdles for an author looking to transform a dissertation into a book is the ability to speak with authority. In some ways, a dissertation is a very long written exam—a display of knowledge for which a PhD student must show mastery. That is not what a book is. A book is meant to provide a sustained argument that provides insight to the reader. The author of a book is already deemed to be an expert; that’s why a press has agreed to publish their book. The audience of a dissertation might be a committee of three people, whereas the audience of a book is (in theory) hundreds or thousands of readers. Many of the conventions of a dissertation, such as literature review, use of jargon, methods review, study design review, etc., are not necessary to include in a book (or, in the case of the methods, can be put into an appendix). A dissertation usually ends with an original argument whereas a good book should begin with a novel argument. Finally, a dissertation does not need to be written with readability in mind, but a book should be crafted to be an engaging read. In short, if you write a boring dissertation you can still get your degree, but if you write a boring book no one will want to read it. If you write a dissertation, you think of yourself as a graduate student (and you are), but when you write a book you can and should think of yourself as an author, an expert on a given topic with something original, even exciting, to say.
—NYU Press, November 2020
Each press has its own policies regarding dissertations, but most university presses will not publish an unrevised dissertation. There are a number of helpful guides to revising a dissertation into a book that you might consider reading as you make a plan for revision—for example, William Germano’s From Dissertation to Book and Beth Luey’s Revising Your Dissertation: Advice from Leading Editors.