Dissertations are unpublished book-length manuscripts completed in order to earn a Ph.D. Master Degree theses are generally shorter, focused and well-documented research papers. Both are often the most cutting-edge and focused work on their topics, so they are valuable as research sources, and also provide templates for students writing theses and dissertations.
Various subject-based databases index and abstract dissertations and some theses that you can use as sources for your research and templates for your own theses or capstone papers. These include:
ProQuest Dissertations and Theses
The Dissertations and Theses database from ProQuest cites 2.3 million works issued by graduate institutions in North America and beyond from 1861 to the present. PDF full texts of most UC dissertations starting about 1997 are available online at no charge.
Center for Research Libraries
CRL is a good source for foreign dissertations; our CRL membership provides free loans for UCSD researchers.
University of California ETDs
To limit to ETDs, click on the thesis box in the menu on the left. To limit to a particular campus, select the drop down option and the campus you want to search. To limit to MA Theses and dissertations in a particular field, put in the department into the search box in the upper right-hand corner and select "This Series," rather than "All of e-Scholarship" (so that you will still be searching within UCSD dissertations and theses only). To limit just to MA Theses, search for Thesis and the department (Thesis "Latin American Studies") OR Master and the department (ie Master "Latin American Studies"). As with the search for dissertations and theses, make sure that you select the "This Series" button.
Undergraduate Theses: Although there is no UC repository for undergraduate theses, this guide points to two (and there are certainly more) places to find some undergraduate theses to get an idea of the scope and format of such works. One is the Claremont Colleges Theses and Dissertations Repository (select any of the collections with senior theses and try searching by keywords to find relevant examples. Note that the various colleges tend to emphasize different subject areas (some, for example, have more STEM fields whereas others are more focused on the Social Sciences or the humanities). The other is the UCSD Department of Political Science's Page on its Senior Honors Program.
For more information on Theses and Dissertations see the Library's Research Guide on Writing Dissertations and Theses.