• Hold down the Ctrl key and left-click a link or middle-click a link to open a link or bookmark in a new tab.
• Hold down the Shift key in addition to the Ctrl left-click or middle-click to toggle loading in the background.
• Links that do not specify a target window open by default in the current tab.

• http://kb.mozillazine.org/browser.link.open_newwindow
• http://kb.mozillazine.org/browser.link.open_newwindow.restriction

• http://kb.mozillazine.org/about:config

You can make a link open in a new tab by holding Ctrl when left-clicking the link, or by clicking the link with the middle mouse button.

Beyond that, you can use an Add-on to automate this. I believe the highly-used Tab Mix Plus add-on has this function, along with a host of other features. If that seems like overkill, Open Link In New Tab sounds more focused.

I use the Ctrl option but sometimes I forget. As I indicated in my post, I have Tab Mix Plus, and figured I should be able to set if to "open in a new tab" by default; but can't find the option.

YES !! I used the Ctrl key and it works great !! Thanks guys !!

I don't want to have to remember to hold down the ctr button or to rightclick to get the new site to open in a new tab. I want it to be automated, like it used to be.

When I click Options/settings/tabs, i get to a list of boxes that can be checked.

One of then is "open new tabs instead of new windows". I naturally have that checked.

However, there is no option to "open new tab instead of overriding current tab", which is what I want, and how it used to be before the last updates.

I actually did install the app "open link in new tab" suggested bt Optional, which sounded like just what I needed. Then I rebooted Firefox, as per instruction. And it still overrides the old window!

Maybe my computer is hexed?

The setting in Firefox/Tools > Options > Tabs only applies to links that specify a target window. All other will open in the same tab.

You need an extension if you want to open all links in a new window.