Guild Wars 2

My friend just recently received GW2 and installed it today. After taking a reprieve from the game myself, the server I play on, Crystal Desert, has become full and he cannot join. Is there anyway he can join me without having for me to switch worlds?

There’s no way for him to join a server listed as “full”, although in the future that might be possible with the guesting process.

For now, you have to wait until the population drops from “full” to “very high” or “high”, at which point he can transfer to your server (the population shifts during the course of the day), or you will have to both choose a world with a lower population to play together. Right now server transfers are free and can be performed once every 7 days.

yes, he can try at other times. Server populations are varying. So on different daytimes he might get a chance.
Be aware that it may take some time and some tries as well.

That is what official will answer too.