Recruiting department will contact you to do a telephone screen. If you get through that, you'll be invited in. Depending on which department you interview with, you may be asked back for two or more interviews. They do behavioral interviewing, so be prepared with anecdotal information (i.e., tell me about a time when...). it is expected that you will display knowledge and expertise of the HR situations you describe. You should be able to discuss basic HR concerns, such as FMLA, ADA, policy development, handbook requirements, etc.

It is very formulaic. Not very conversational. Managers pretty much have a good idea of who they want to hire so interviewing can be seen as a waste of time. Lots of situational questions are asked. Be sure to have extensive employee relations experience or they will just go through the motions with you and won't consider you at all.