(This post originally started as a response to a query on an email listserv, but it occurred to me that it made a pretty good Library Ass posting in its own right on the topic of interviewing prospective student workers. So here it is!)
I am responsible for hiring and supervising between 8-12 student workers and a handful of temps. My desk is a point of service for both regular library patrons accessing rare or noncirculating materials as well as visiting researchers who access the entire collection through us, so there is a very large customer service component which requires a certain kind of temperament and/or work ethic. The trouble is that library jobs tend to be the lowest paid work-study jobs on our campus, which means that many times our "interviewing" process actually works in reverse, as prospective student employees shop around for the best gig for that academic year.
That being said, there are a few standard questions that I ask:
1. "How comfortable are you in a library?" While we try to keep our desk covered with one staff member and one student at all times, during breaks or book pages it's entirely possible that the student worker will be manning the desk on his/her own and subject to all manners of informational questions. Bearing in mind that by the time patrons get to our desk they've already been bounced around a couple of times we try not to send them away without the answers they need (with the exception of bonafide reference questions, of course), so that requires a certain familiarity with how our library and university library system functions. It's okay if a prospective student employee has no such experience or familiarity, provided that he or she demonstrates an eagerness to learn those skills during the interview.
2. "Do you consider yourself a 'people' person?" We are public service desk that interacts with scholars visiting from all over the world and who aren't afraid to make unflattering comparisons if we fail to live up to the other members of our peer group. As luck would have it, these same patrons tend to be the ones who require the most hand-holding, especially where technology is concerned (sometimes there is also a language barrier or physical disability). While our Circ Desk is much more production-oriented and is trained to make quick and efficient referrals when needed, in the reading room we need student workers who are above all patient, understanding, and willing to go the extra mile.
3. "How well can you multitask/prioritize?" Although our reading room has an hourly paging schedule and periodic deliveries from off-site storage, there is absolutely no regularity to our workflow from day to day, even hour to hour. I'm impressed that people can dash off an email while staffing our desk, let alone read a book for class or write a paper, but as long as students give their undivided attention to any patrons who comes to the desk we're pretty much laissez-faire about what they can and can't do with their free time. We're well aware of the fact that due to our abysmal wages we need to sell this fact in order to attract and keep a regular schedule of students, but that requires a certain kind of worker who is able to keep one eye or ear open while cranking out a problem set at the last minute.
4. (Perhaps most importantly of all) "Can you stay in touch and keep us in the loop?" I don't pretend that the 4-10 hours that our students work for us every week is the most important thing in their lives, and I'm not particularly interested in trying to teach them 'life lessons' about keeping a job in the real world. What I do expect, however, is for my students to read every email I send and respond when asked to, as well as give me advance notice of any upcoming problems in their schedule so that I can plan accordingly. I also ask prospective students how comfortable they feel with being contacted via IM or through Facebook for work matters, as I'm well aware that email is increasingly taking a backseat to social messaging. If through the initial contact period I suspect that there will be a problem on this front, I tend to turn away the students right then and there.
In truth, however, it's pretty hard to tank an interview with me. This isn't simply a function of campus economics, but an acknowledgment on my part of the limitations of trying to evaluate an employee's worth in the space of the first 10-20 minutes that we know one another. I've had students who interviewed impressively but were absolute basket cases on the job and vice versa, so unless there are any serious warning flags during the hiring process I tend to err on the somewhat lenient side. I guess I'm just a big softee that way...