How do I address an invitation when I don't know the guest's plus-one?

When you do not know the plus-one's name, handle it on the inner envelope so the guest still feels welcomed.

• Outer envelope: write the invited guest's full name.
• Inner envelope: add "and Guest" on the line below their name.
• Better still, ask for the plus-one's name whenever you can.
• Real names make the invitation feel personal and help with seating charts later.