How can I tell if an article is peer reviewed?

Ulrich's Periodical Directory can tell you if the journal that your article comes from is peer reviewed.

Look up the journal title Ulrich's. Remember that you are searching for the journal that the article comes from, not the article itself.

The referree jersey icon  tells you if the journal is peer reviewed.

Not every kind of article published in a peer reviewed journal is peer reviewed. Articles like editorials and book reviews do not go through the peer review process, but primary research articles do.