Having a master's degree in a particular field already demonstrates that you have extensive knowledge in that subject area -- but adding information about your master's thesis on your resume can help drive the point home even more. It's especially helpful to include information about your thesis on the resume if that thesis relates closely to the job for which you're now applying -- but in any case, it's worth including it in your resume's "Education" section.
Where to Include the Thesis
In the "Education" section of your resume, list the schools you've attended in reverse chronological order. Start with the name of the institution, followed by the degree you earned and the area or subject you specialized in. If you're trying to save space, type "Thesis:" on the same line, and then include the title of your master's thesis. If you have available space -- or you want to make the information about your thesis stand out more for the employer -- skip a line under the basic information about your master's degree, hit "Tab" on your keyboard to create an indentation, and then type "Masters Thesis:" followed by its title. For even more emphasis, type one succinct line describing the nature of the thesis. To make it stand out even more, describe particular points from the thesis in your job application cover letter.