Primary and Secondary Sources

The Basics

Primary sources are original, uninterpreted information.

Unedited, firsthand access to words, images, or objects created by persons directly involved in an activity or event or speaking directly for a group. This is information before it has been analyzed, interpreted, commented upon, spun, or repackaged. Depending upon the context, these may include paintings, interviews, works of fiction, research reports, sales receipts, speeches, letters, e-mails, and others.

Think of physical evidence or eyewitness testimony in a court trial.

Secondary sources interpret, analyze or summarize.

Commentary upon, or analysis of, events, ideas, or primary sources. Because they are often written significantly after events by parties not directly involved but who have special expertise, they may provide historical context or critical perspectives.

Think of a lawyer's final summation or jury discussion in a court trial.

Identifying Primary and Secondary Sources

What is a primary source?

A primary source is firsthand testimony or direct evidence concerning a topic, an event, a person's life, original works of literature, and historical facts. It consists of original materials that have not been filtered through interpretation, condensation, evaluation or any type of commentary. Primary sources are usually the first formal appearance of results and offer an immediate picture of the topic under investigation.


Proceedings and minutes Letters and Correspondence
Journal articles reporting research results Original documents (birth certificate, transcripts)
Scientific Journal articles reporting research results  
Technical reports Photographs and works of art
Patents Speeches
Sets of data such as Census Statistics Autobiographies, memoirs
Works of literature (poems or fiction) Eyewitness accounts
Diaries Constitution, statutes
Interviews, surveys Treaties

What is a secondary source?

A secondary source is information about primary, or original information, which usually has been modified, selected, or rearranged after the fact, for a specific purpose or audience. It can be a description, an interpretation, an analysis, a commentary and an evaluation of an historical event or phenomenon, or the original writing of an author.


Biographies Indexes and Abstracts
Bibliographies Chronologies
Encyclopedia articles Commentaries
Dictionaries Dissertations and Thesis
Directories Monographs (non fiction)
Editorials Review articles and Literature review
Textbooks Work of criticism and interpretation
Periodical articles Almanacs and Fact books

Please note:

Primary sources tend to stand on their own, while secondary sources are based on other sources, but it is not always easy to discern the difference between the two. The same document, or other piece of evidence, may be a primary source to one researcher and a secondary source to another.

For instance: If you are doing research on Pearl Harbor, a newspaper article commemorating December 7th, 1941 is a secondary source. An article dated of December 7th, 1941 and reporting the attack on Pearl Harbor is a primary source.

Search WebCat to find primary sources:

While performing a subject search in WebCat, use the LIBRARY OF CONGRESS Library of Congress subdivisions below to retrieve primary material on your topic:

Diaries Case studies
Personal narratives Songs and music
Correspondence Public opinion
Photography Caricatures and cartoons
Interviews Pictorial works
Underground literature Exhibitions --posters
Anecdotes Sermons

Adapted from:
Loyola University,, 10/16/05