Europe: DART-Europe E-Theses Portal
http://www.dart-europe.eu/basic-search.php
Access to over 500,000 full-text theses from over 500 European universities.

Proquest Dissertations & Theses Full Text
http://libweb.lib.buffalo.edu/pdp/index.asp?ID=125
Provides indexing and access to United States and Canadian dissertations.

Open Access Theses and Dissertations
http://oatd.org/
OATD aims to be the best possible resource for finding open access graduate theses and dissertations published around the world. Metadata (information about the theses) comes from over 600 colleges, universities, and research institutions.

Openthesis
http://www.openthesis.org/
Free repository of theses, dissertations, and other academic documents, coupled with powerful search, organization, and collaboration tools.

Networked Digital Library of Theses and Dissertations (NDLTD)
http://www.ndltd.org/resources/find-etds
An international organization dedicated to promoting the adoption, creation, use, dissemination, and preservation of electronic theses and dissertations (ETDs). Provides links to resources to find available open-access electronic theses and dissertations.

Great Britain and Ireland: Index to Theses in Great Britain and Ireland http://libweb.lib.buffalo.edu/pdp/index.asp?ID=219
Leads to citations (and in most cases, abstracts) of dissertations and master's theses completed at British and Irish universities. Also provides links to over 70,000 full-text theses available online for free downloads from university repositories as well as EThOS (http://ethos.bl.uk).

EThOS
http://ethos.bl.uk/
The British Library’s Electronic Theses Online Service.  Search across over 350,000 theses and order full-text.

Spain: Tesis Doctorales: TESEO
http://www.educacion.gob.es/teseo/
Abstracts of theses from Spanish universities.

Spain: TDX – Tesis Doctorals in Xarxa
http://www.tdx.cat/
Doctoral theses presented at some Spanish universities.

France: Thèses
http://www.theses.fr/
Citations and some full-text French theses.

Germany: Sammlung Digitaler Dissertationen in Deutschland
http://deposit.ddb.de:8080/cocoon/xml-xsl/homepage/texte-neu/quellen.xml
Gateway to online dissertation sites of many German universities.

Scandinavia: DIVA
http://www.diva-portal.org/smash/search.jsf
Provides access to ETDs and research publications written at 26 institutions in Scandinavia.

Netherlands: NARCIS
http://www.narcis.nl/?Language=en
Provides access to ETDs produced in the Netherlands, as well as access to a variety of other research and data sets.

Portugal: RCAAP - Repositório Científico de Acesso Aberto de Portugal
http://www.rcaap.pt/
This portal offers a union catalog with digital contents from more than 30 Portuguese institutions; you can restrict a search to theses and dissertations.

Italy: Tesionline
http://www.tesionline.it/default/index.asp
Italian service which sells theses and dissertations; free previews available for most items.

Finland: E-Thesis, Finland
http://ethesis.helsinki.fi/en/
University of Helsinki theses and dissertations published since 1999 open access.