There is no single source for a comprehensive dissertation search. WorldCat and ProQuest Digital Dissertations and Theses Full Text include most American dissertations. Dissertations @ The Center for Research Libraries lends non-American dissertations to member borrowers. Library catalogs and specialized repositories contain other titles. Request any dissertation through Interlibrary Loan. Though not every title is available through ILL, it is worth a try.
Graduate Center dissertations from 1988 to the present are available for browsing in the Dissertation Reading Room on the first floor of the library. If you do not know the year of a dissertation, check the author or title in the CUNY Catalog or in Digital Dissertations.
For more information about submitting your own thesis or dissertation, see the Dissertations & Theses guide.