First, you can only do this if each iframe's page is stored on the same domain name as the other and as the page that they're both being framed on. Second, you should be able to do this by doing something like.. parent.document.getElementById('2nd_iframe_id').src = 'new page url'; Code (markup): You'd call that snippet of JavaScript when the person clicks the button in the other iframe. If it doesn't work as I typed it then sorry, I haven't really ever worked with iframes because I don't like them so I'm not sure if doing ".src = 'new url'" will update it immediately, though it should.