Get feedback and criticism on your thesis from your adviser and other faculty members. Take their advice and rewrite or rework any sections that are vague or confusing. Solicit feedback from fellow students. Consider hiring a professional editor or a graduate student in your college's English department to make sure your grammar, punctuation and style are top-notch.
Research academic and university presses. The Association of American University Presses offers a comprehensive list of U.S. academic presses, along with links to their individual websites. Submission guidelines typically appear on each publisher's site. If you're interested in a press that does not list its submission requirements, email editors directly. Note each press's genres. For example, don't contact a publisher that specializes in poetry if you're looking for a press to publish your microbiology thesis.
Send query letters--one-page pitches describing your thesis--to publishers. Large commercial publishers often will not review material by authors who are not represented by an agent, but academic presses are more willing to do so, especially since they publish many works by professors, graduate students and recent college graduates. Some publishers will request that you submit sample chapters or detailed outlines of your book, while others will only want a one- or two-paragraph summary of the work, along with a brief author bio that lists your writing credits and any awards your writing has received. Be sure to follow each press's instructions carefully.
Wait for a response. The review process can take several months or longer. Publishers sometimes list review times on their websites, but not always. Academic and university presses in particular are often understaffed, and acquisitions editors sometimes struggle to keep up with the number of submissions. If you haven't received a reply in four to six months, send a polite follow-up letter, along with your original query letter.
Sign a contract. If you receive a call or email from an editor offering you a book deal, you will receive a contract either by U.S. mail or email. To educate yourself and to receive the best contract terms possible, visit your local library or bookstore and read books on publishing language and contracts. You can also ask fellow authors to review the contract for you, or you can hire an attorney to advise you regarding royalties, length of contract and any publishing rights you might want to keep for yourself.