What they ask you to call them. Call them by their chosen name and pronouns, unless there's a situation where they aren't out yet (e.g. "Sue is a girl, but her family still thinks she is a boy, so I will call her a boy in front of her family until she is ready to tell them who she really is"). Their real name and pronouns are the ones that fit who they are inside, regardless of their genitals. For example, if someone was born with the name Ann, but then realizes he is actually Adrien, his real name is Adrien and you'd call him a "trans guy." Check out Understand the Basics of Transgender Terminology . And when in doubt, just take the person aside, explain that you don't know the right language, and politely ask them what they'd like to be called. If you mean well, that makes a difference, and it's okay if it takes you a little practice to get it down.