I interviewed on 2 different occasions for this position. The first interview took place at the University I graduated from. The second interview took place in New Jersey. The first interview was very easy going. We discussed my resume, past job experience, job location preferences, etc. I do not recall any behavioral or "what if" questions, but one should always be prepared for those. The second interview was at GAF Headquarters, and it took half a day. I interviewed with 6 different people in various levels of management. Again, the interviews were very easy going and enjoyable.