Turn on the profanity filter. WoW's profanity filter is on by default, but many players disable it as soon as they realize it's bowdlerizing their chat text. If your kids are beginning to eye their own characters, you may want to revisit the profanity filter. Hit your Escape key to go the Main Menu, and go to Interface Options, then Advanced Options. Look for the Mature Language Filter in the Chat section.
Be forewarned that the existence of a profanity filter does not give players an excuse to use inappropriate language in game. "The Mature Language Filter is only an extra means of protection from obscenities in chat channels, not an excuse to use them," says Blizzard. "All players need to adhere to the World of Warcraft Harassment Policy at all times."
Leave the public chat channels. Whether you're trying to dodge Barrens chatter for a more peaceful, immersive play session or trying to protect young ears from the kind of ear-blistering talk that's likely to erupt in zones frequented by immature players (Barrens and Elwynn Forest, we're looking at you), sometimes it's easier to simply leave the General and Trade channels. To leave General chat, type /leave general; to rejoin, type /join general. Note that you may not be able to rejoin Trade or city-specific channels unless you are in that city.
Ignore problem players. You can keep from seeing chat messages (both public and private) from players who annoy you by adding them to your ignore list. To ignore a player, type /ignore playername. You can view your Ignore list by clicking your Social button (the same place you'd look for your Friends list).
WoW offers a relatively small ignore list. If you run out of room on your list, you may find you need to remove some players from your list or install an add-on that allows you to ignore more players.
Lock voice chat.
Most parents aren't crazy about the idea of their kids chatting it up with strangers via voice chat. To disable voice chat, hit the Escape key to access the Main Menu, go to Sound & Voice, hit the Voice tab at the bottom and then uncheck the Enable Voice Chat box at the top.