The first thing to remember is that a thesis is the point the author is trying to prove. That means that a topic, which can be expressed in a phrase, like alcoholism or effect of corruption on poverty, is not a thesis. A thesis can only be expressed by a complete, declarative sentence (not a question, either). So be sure to write out a complete sentence when identifying the sources thesis. (Review What is a Thesis for more details.)
Often all you need to identify the thesis of an article is the abstractthe brief summary, usually just a short paragraph, provided with the listing of many articles in most databases. This explains the main idea of the article and states what point it is trying to prove.
However, an abstract is not always provided. In those cases, you may need to read the first few paragraphs to get the gist of the article. This is typically where the author will lay out the argument and, again, state the point that they are trying to prove. In more difficult cases it may be necessary to read the conclusion as well, since this is often where they sum up the argument one last time. Sometimes its clearer in the conclusion than in the introduction.
With books, the thesis may be stated on the back, on the jacket flap, in the preface or introduction, or early on in the first chapter. On the back and on the jacket look for phrases like the author argues that In the preface, introduction or first chapter, look for I argue or similar phrases.
Keep in mind: Reference works do not have theses. Remember the definition of a thesis: a point that an essay is trying to prove. Reference works donít try to prove a point. They simply report information. Usually itís the more in-depth general interest works, and especially the scholarly sources, that have theses. So those are the ones youíll want to focus on.
Note: If the full text of the article is not available on line, or if youre looking at a listing for a book, it will be necessary for you to go to the library and get the hard copy off the shelf in order to identify the thesis. In a worst-case scenario, our library wont have the source, and it may be necessary to go to another library such as the UW library to find it. Plan your time accordingly!