First I was called about 2 months after I applied to ask if I wanted to attend the assessment centre, as well as being asked a couple of questions about me/the job/the company. The assessment centre lasted two days. The first included an introduction to the company, a site tour and then we were taken to a local (very nice) hotel where the assessment centre took place. There was a dinner with the other candidates and senior staff members. At the actual assessment centre on the second day there was a couple of group exercises about problem solving/analytical thinking, an in-tray exercise and personality test. After that four candidates were selected to go to the final interview, which was a typical competency questions interview, sort of focused on personality again, with the two managers. I've been to quite a few assessment centres/interviews and IPSEN's was the best by far. It's about getting you to shine and is much less like the hunger games than everywhere else I applied to.