As you are researching topics you will discover a variety of literature, including articles, books, dissertations, conference reports, government documents, and more. 

If your goal is to limit your search to the dissertation literature, see the options below. 
Note:  There is no single resource in which all dissertations are indexed and freely available.
 

ASU and other UNC school dissertations (online):

• To find ASU dissertations from ~2010 to the present, search NC Docks.  Limit to ASU, Type, and Doctoral Dissertations:

• To find older ASU dissertations:
• If you locate a dissertation in the library online catalog, check the availability.
• For the example below, clicking View Online will lead you to the electronic version on NC DOCKS.
• ASU Spec UArchives - LD 175 .D6 no. 137 is the call number for the physical dissertation.  You can make an appointment to view a paper copy of the item in the Special Collections Research Center on the 4th floor of Belk Library.  

Proquest's Dissertation and Thesis Open (PQDT Open) database provides the full text of open access dissertations and theses free of charge.  (It is a subset of a larger ProQuest subscription product.)

• Search by topic or see the other search options.
• Open Access full-text dissertations display in the search results.

Purchasing a dissertation is an option via ProQuest Order a Dissertation.

ERIC database - There is a option to limit by Publication Type and the search results will then display only dissertations.

• Enter your topic.
• Select Dissertations/Theses - Doctoral Dissertations OR one of the other choices from the Pub Type listing.
• Consider if you want to also select Full Text.  If you do not need full text immediately, you can use ILLiad to request a dissertation via interlibrary loan.
• The results page provides citations & abstracts.  Full-text availability will have links, Full Text from ERIC.

WorldCat (First Search) - contains worldwide library records.  You can limit to Internet Resources and by Publication Type.

• Search for:  Enter a topic 
• Limit type to:  Internet Resources
• Subtype limits:  Any Content >> select Thesis/dissertation from the drop down menu
• The results page will provide dissertation citations & abstracts.  Some of the Access links will be to full-text dissertations, abstracts only, or commercial pay sites.