Caltech has a sizable Human Resources department. I applied for the position in late December and was not contacted until late February. The HR person who assisted me was very pleasant and detailed and sent over some instructions for the interview; where to park, where to go, etc. She explained the position thoroughly and advised me to look over their website to become familiar with this famous campus.
When I arrived, I did not meet the HR person I spoke with, rather I was given a map to go ahead and meet with the interviewer immediately. The position I was interviewing for was in the division of math, physics and astronomy (so cool!) and their style was very relaxed. My interview lasted almost two hours, but the interviewer was very welcoming and it helped that their dress code is none.
Ultimately, I came up short with some of the skills they needed, but overall, it was a basic interview.
Questions asked:
Tell me about a particular achievement in your previous job?
What are your weak points?
How do you deal with a manager that is practically non-existent?
Do you work well on your own?
Tell me why you are the person for this position?
Hope this helps! I really had a great experience and if you are looking for a position in an academic setting, look into this place. The campus is beautiful, the people are beyond brainy and the benefits are excellent. Looks like pay is good too. Another bonus - not every position has to go through a background check or drug test.