I had a phone interview with HR, then an hour long interview with 2 managers about a week later, then 2.5 hrs with 5 different people from people I would be working with up to the director about a week after that. Everyone was very friendly but definitely asked a variety of thorough questions trying to get to know me/my background better. It was obvious everyone genuinely liked working there and believed in what they are doing. They wanted to be thorough in the interview process to make sure the candidate was a good fit. I appreciate that because it gave me an opportunity to talk with several different people at all levels to get a sense of the overall culture.