Hello Alister. PDF aren't readable on most web browsers. You need a PDF reading application or plugin to do that. Hopefully this support article is what you need: http://support.mozilla.com/en-US/kb/Opening+PDF+files+within+Firefox For future reference, always search the knowledge base prior to asking a question. After all, the search bar is right there, huge, in your face, and the "ask a question" button is tiny and hard to find.