This is an account of the problem to be studied and of the resources available to undertake that study. The proposal usually consists of two or three pages with an attached bibliography. You should submit your proposal only after discussions with an adviser and perhaps other faculty.
Pro-tip: Be sure to participate in the anthropology research workshops. Browsing current journals in your area (or areas) of interest and talking to relevant faculty will help you come up with ideas.
Conducting field work before you start writing your thesis. You should consult faculty members long before you begin your senior year. Theses that require extensive field research must be undertaken between the junior and senior years. Though such theses may require some work that extends into the senior year, you should never expect to conduct substantial field research while writing the thesis.
You should consider the availability of published materials. The library is able to order a limited amount of books on your topic. The first research workshop will help you begin to assess what kinds of resources are available for the topics you are considering. You can also consult the Reed Library and the Anthropology Librarian, Ann Matsushima Chiu. Interlibrary loan materials are available to students. However, even the best libraries might not be able to handle esoteric topics; these should be avoided for anthropology theses at the B.A. level.
Writing The Thesis
Pro-tip: As you begin reading for your thesis, you should concurrently start writing. Writing a little bit every day helps keep the workload manageable. A thesis is usually a much larger project than a course paper and the strategy that has worked well for you on course papers may not work as well for the thesis.
Reviewing the Relevant Literature
Search broadly and deeply to find out what others have discovered about your question.
Connect with the Anthropology Librarian, Ann Matsushima Chiu (Office: Library193) who can help you identify the necessary tools to conduct this search as efficiently as possible. If you cast your net broadly at the beginning, you are less likely to be surprised at the end to find that someone else has done research that diminishes the impact or credibility of your own work.
Keep detailed notes on everything you read. This includes full bibliographic information in the appropriate format; Citation software such Zotero can be very useful for this purpose! (Be very sure that your notes distinguish between the author's words and your own. Plagiarism can arise inadvertently if a student uses in the thesis a passage from his or her notes without realizing that it was a near-exact quotation copied into the notes months earlier.)
Pro-tip: Photocopy or otherwise preserve all passages you think you might want to quote and any tables that contain useful data. The notes you make as you read can be the basis of a literature-review chapter (if you choose to include one).