First, I had a 20 min on-campus screening interview at University. My experience doesn't seem that typical from talking to a lot of other candidates, or maybe it was only typical when Microsoft is hiring large groups (there were at least 50 candidates) for their $$ divisions. What happened next is after a 2 weeks, there was a callback to interview in Redmond. It was a planned day that started that was split in half from 9AM - 6PM. Half of the group started interviewing first, the other half had talks about how great working at Microsoft is. The actual interview process was 4 people, 45-min each with 15-min break in between. Fairly easy test questions on how to test (insert physical object/software part here) and also given some code to debug/show your approach to know when the code has been tested "sufficiently." At the end of the day, there is about an hour wait while interviewers deliberated and called dibs (multiple teams were interviewing) on the people they interviewed. Then all of us that got offers were called into a room to get presented with our managers who congratulated us and had a chat about the team, offer details, etc. My only advice is to relax, be methodical and organized in your testing of objects questions and breakdown all the problems, no matter how simple they seem - trust me.