What should I expect at an interview for a temp /staffing agency?

Answer 1

They don't do much in the way of interviews, everybody gets hired. You fill out the application and they make copies of your drivers license and auto insurance. If you have work related certifications, they want copies of those. If you do office work, they ask about your computer experience and typing speed, and if you work industrial, they ask if you have steel toed boots.
I worked with several temp agencies while going to college and I never had a real hiring interview.

Answer 2

Expect to be there awhile. They usually test your skills depending on what your applying for. It can take up to 2 hours or more. Dress professionally. Treat it as you would a regular job because most large companies work with head hunters. They may place you with an awesome company that could lead to a permanent job. Thats how I got in at the best company I have ever worked for. Good luck!!!