It's a three part interview: HR (basic, nothing special), hiring manager, then invitation to go in and meet other managers/director.

Phone screen, followed by 3 on-site interviews. First round was one-on-one interview with the manager, Second was a group interview with colleagues, Third was one-on-one with the Director. Lots of thoughtful questions to gauge intelligence and whether I would be a good fit for the department's culture. After I accepted the offer, I had to submit to background and drug testing.