I figured I would post this since I only found one place that ever talked about it. I was doing includes in PHP with query string on them. This necessitates including the file with the full URL (http://domain.tld/script.php?foo=foo1&bar=bar1). However, when including something with the full URL, sessions in the included file do not work anymore. This gave me fits for about two days before I found this out. I got around it by passing the variables into the included file another way (due to the way I am doing my templating), but you could probably just include the file after setting the variables, as the included file will read those variables from the including file.