Dissertation and Theses - Full Text (ProQuest) contains entries with information about doctoral dissertations and master's theses. It is the same database as Dissertation Abstracts, but with the significant advantage that titles published since 1997 are available in PDF digital format and have 24 page previews available.
If there is no option to download the full text of a post-1997 dissertation, this means that the author has refused to grant these rights.
DART-Europe E-theses Portal
British Library Integrated Catalogue
CRL - Center for Research Libraries Catalog
Index to Theses ... Accepted for Higher Degrees by the Universities of Great Britain and Ireland
Networked Digital Library of Theses and Dissertations Union Catalog
Sudoc (French theses page) SUDOC: An online catalog to holdings at French academic libraries, SUDOC covers theses completed in France since 1972 (for Humanities and Social Sciences). Search by author, title, and abstract. Limit your search to theses by clicking on "Options" on the right hand corner of the page and limiting your search to "Thèses;" click on "Appliquer" to save your selection and proceed with the search.
Système universitaire de documentation Le catalogue contient plus de 5 millions de références de monographies, thèses, périodiques et autres types de documents avec leurs localisations
Theses Canada Portal