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.