Assuming you are using Firefox 2, installation should be extremely simple: merely go to the Zotero home page, click on the “Download” button, click “Install” after Firefox has downloaded Zotero, and then restart Firefox. You should now see the “Zotero” logo at the bottom of your Firefox window.

When you first try to download Zotero, you may receive the following message, which appears in a narrow yellow band at the top of the web page: “Firefox prevented this site from asking you to install software on your computer.”

If you receive this message, you'll also see an “Edit options…” button. Click this button, then click “Allow” and “Close.”

Now try downloading Zotero again. You should have no problems this time.

On rare occasions, you may get other kinds of error messages. The most common of these (rare) messages is a ”-228 error,” which prevents Zotero from downloading. There are a variety of reasons for this message, ranging from security software running on your computer to more technical considerations.

There are two alternative download methods if you continue to have problems:

1. Download Zotero from our home page by right-clicking the “Download” button on a PC or control-clicking the “Download” button on a Mac, then selecting the save option. Save the Zotero extension file (which ends in .xpi—be careful you don't save the image of the “Download” button by accident) to your desktop, then drag and drop that file onto an open Firefox window.
2. A less preferred way: try installing it from the Firefox Add-ons site rather than zotero.org. The disadvantage of downloading Zotero from the Mozilla/Firefox site is that you'll receive notifications of new versions of Zotero much later than users who download it from zotero.org. (Every time we make even a minor revision to the software, we have to submit it for review to Mozilla, which can take some time to post it to their site.)