I was contacted by a recruiter first by email. I replied, who then set up a phone screen, which then led to a physical interview being set up after a day. Because of logistics, the interview didn't occur until the next week.
I have to admit that at first I was intimidated. They didn't seemed impressed, so when I completed the interview my instinct was that I didn't get the position. They also seemed amused at several items in my resume, but I also tried to ensure I demonstrated my competence.
Most of their questions were about my background and to describe my previous research experience, as well as various protocols. Most of my questions were about the nature of the work I would be potentially assigned to. Because there were a variety of teams that contractors can be potentially assigned to, they were rather vague about the nature of the chemical problems that needed solving, and how they might be solved, but because I am see myself as a junior chemist who likes to carve out specifically the constraints of the problems I'm solving, the interview ended up proceeding down a technical path of inquiry, something that I think worked out in my favor.