Tim Pritlove wrote: Apache's mod_rewrite un-escapes various hex-encoded characters which have special meaning in URLs, most insidiously the question mark (?) and ampersand (&). The result of this is that an incoming URL like: /wiki/AT%26T gets rewritten to: /mediawiki/index.php?title=AT&T whose query string gets parsed into this list: title => 'AT' T => '' There's an easy workaround, and a more complete fix. The easy workaround is (at least if you're using PHP as an Apache module) to switch to using the PATH_INFO-style URLs: RewriteRule ^/wiki/?(.*)$ /mediawiki/index.php/$1 [QSA,L] The '&' character has no special meaning in the _path_ part of the URL so the rewritten form works: /mediawiki/index.php/AT&T However now you'll find that titles with question marks fail similarly, because the question mark separates the path from the query string: /wiki/Got_Milk%3F_(advertising_slogan) /mediawiki/index.php/Got_Milk?_(advertising_slogan) On our own servers we use a patched version of Apache which adds a rewrite processing function to specifically re-escape the ampersand into %26. You'll find a patch for Apache 1.3.x in the MediaWiki distribution as maintenance/apache-ampersand.diff Use is something like: RewriteMap ampescape int:ampescape RewriteRule ^/wiki/(.*)$ /w/index.php?title=${ampescape:$1} [QSA,L] Alternatively, you might try replacing the rewrite rule with an alias to index.php: Alias /wiki /var/www/mediawiki/index.php or other such tricks to use the built-in PATH_INFO usage. -- brion vibber (brion @ pobox.com)