Theses and dissertations are written by students (theses by graduates and sometimes upper level undergraduates, and dissertations by doctoral students) and reviewed by a faculty review committee. They can be useful for finding unpublished research. They generally have lengthy bibliographies at the end that can be useful if you are pursuing a related topic.
Many Art and Architecture History theses are cataloged and in the library stacks. These titles can be found by author and title search in LibSearch to find the call number and library location. By searching the keywords "art history oregon" and then selecting the material type "theses and dissertations", one can find a listing of UO art history theses including the Scholars Bank entries..