When you are searching one of the Library databases such as Academic Search Complete, click on the title of the article to display the article record.
Click on the name of the journal. It will display information about the journal, including whether or not it is a peer-reviewed journal. You can also limit your search in the database to peer-reviewed journals before you begin searching.
Another way to find out if an article is peer-reviewed is to find the homepage of the journal where the article originally appeared in print. Once you've located the journal's website, you should find information concerning whether the journal is peer-reviewed or not. (Terms like refereed or scholarly might be used in place of peer-reviewed).
Remember, not all information within a scholarly journal is peer-reviewed. Editorials, letters to the editor, and book reviews are not peer-reviewed.