Digital Dissertations (Dissertation Abstracts)
NOTE: On July 21, 2007, ProQuest Digital Dissertations will change search interfaces! Access will be via ProQuest Dissertations & Theses (PQDT) on the ProQuest platform. Indexing (since 1861 and abstracting (since 1980) for doctoral-level dissertations completed at North American universities. Dissertations from selected European universities are also listed. Selected master's theses are included since 1988.

One can search the database by: author, keyword in title and/or abstract, adviser, university code, date, degree. Boolean operators allow for combinations of fields.
Holdings: Indexing 1861-present, abstracts 1980-present, full-text PDF for most Penn dissertations from 1997 to the present.

Music Theory Online Dissertation Index
A list of dissertations in music theory with abstracts.

CRL Foreign Doctoral Dissertations Database
Also search WorldCat. Catalog of non-US dissertations held by Center for Research Libraries. Still in progress, and may be frozen as CRL begins cataloging its 750,000-dissertation backlog in WorldCat.