Is there a way to prevent a 3rd person from joining on Facebook chat?

[Teresa J]

If you're chating with someone on Facebook, is there some way of preventing a 3rd person from joining in and interupting?

[TechGeek01]

A 3rd person cannot join a private chat. They have to be in a group, and you have to be chatting with the group, for multiple people to chat at once.

If, however, you are chatting with someone, and you mean another person popping up and starting a separate chat with you, as far as i know, there is no solution for that. If this is what you mean, you are best to just minimize/close their chat box and ignore them when they pop up.