All University of York PhD and MPhil theses are available via the library catalogue. Masters theses for some subjects are held in the Library for 6 years. 

All York research students registered in or after October 2009 are required to upload their thesis into  White Rose Research Online, a shared online respository for academic publications from the Universities of York, Sheffield and Leeds.

You can also access theses from outside the University:

• British Library EThOS Service 
  Free access to over 300,000 full-text theses from UK universities. You can send a digitization request to the British Library if the thesis you want to view is unavailable online.
• DART-EUROPE E-theses Portal
  A searchable database of details of doctoral-level electronic theses which are held in European repositories. The theses listed are publicly available, in full, without charge. The DART-Europe Portal does not store theses, but it provides a link to at least one electronic copy of every thesis listed in its database.
• Index to Theses
  A comprehensive listing of theses accepted for higher degrees by universities in the United Kingdom and Ireland since 1716. Over half a million theses are listed, with abstracts in most cases.
• Networked Digital Library of Theses and Dissertations
  Search for international theses.