My interview consisted of a phone screening with a MITRE recruiter, that was followed up by a first interview, and a follow interview. The first interview consisted of three sessions, first with an HR rep, second with the team who I would be working with, third with leads from other teams in the department. About a week later I had a second interview with the department heads. Each of the interviews was a mix of people in the room with me and people on via conference call. My first interview was on a Friday, and I was surprised to see how casually dressed the employees were.