Do I let companies know I am interviewing elsewhere?

I am in the middle of looking for new employment and I have had no problem getting interviews, but I have had no offers yet. Do you see it as helpful or hurtful to mention in a job interview that you are interviewing at other firms? I am not suggesting blurting this out at at a random time during the interview, but to casually mention it in the natural flow of the conversation/interview? But I am unsure if the employer would look at this as a positive or negative attribute.

Don't announce it unsolicited, but be prepared to answer

One of my standard questions at an appropriate point in the interview process is, "Do you have any other job applications at a state that might require us to move quicker with our decision making?".  If you get a question like that, then yeah, you'll want to be ready with a brief summary of any other pending job offers.  I usually hear either "I'm not applying to any other jobs" or "I don't have any other offers yet", either of which are fine.  I've gotten one "I'm expecting an offer from another firm within the next few days", which caused us to move quicker on our decision-making (and I replied with "Please feel free to let us know before you accept another offer, so we can discuss the situation").

Overall, you've got to consider what you hope to achieve by revealing the information, unsolicited or otherwise.  I can't see a situation in which revealing the fact that you've got other interviews (or potential offers, or actual offers) would result in a net benefit.  Sure, you could try and scare someone into giving you an offer they wouldn't have otherwise given, but do you really want to work for someone so easily manipulated?  Do you want to be the sort of person that manipulates a situation?

My personal take is that if someone told me, "well, I do have several interviews lined up this week", it would more likely cause me to think "well, he doesn't need us then" rather than "Oh my, this person *must* be good if they can get *multiple* interviews, I must hire them IMMEDIATELY!".  As a data point, I don't recall anyone ever doing that, so I guess it isn't a particularly common thing for people to do.

 If your interviewer asks

 If your interviewer asks about other interviews, then I don't see harm in answering that you're looking at other opportunities - if that is indeed true.  If you're not asked, then I see no benefit to offering that information unsolicited.  

And if you do respond about other opportunities, do not mention if you have an offer or not.  This looks like you're trying to play one company off another.  And I don't believe you're obligated to share that information anyway.  

I wouldn't ask

I wouldn't ask you, as the hiring manager.  We don't have a very long hiring process, takes 2-5 days once formal interviews start.  Often we have a decision within 24 hours.  So, if you have another offer, you'll either accept it within a short amount of time or ask for a few days.  The most I want to give you is 3 because either you want to work for us or you don't.  But, I don't hire very often for C-level positions, I hire clerks and laborers who either want the job or they don't.  YMMV.

If we were talking upper management, I'd be willing to give you more time to decide but I still wouldn't ask if you were interviewing elsewhere.  I'm not competing against them for you.  As the interviewee, you can see it that way.  I prefer to think I am looking for the right fit at the right terms (wages/benefits).  You could be the right fit but the terms just won't work for us.  I've had that happen several times but have gone back to the candidates and found that my "second choice" was as wonderful as I was hoping.

So, I'd keep it to myself, unless directly asked.

If asked...

The MT recommendation is to always directly answer a question if asked. So if you're asked, of course you answer it.

As for volunteering the information, what exactly are you expecting to result from it? I imagine the result won't be what you intend in any case. Keep it to yourself. If you interview with me and aren't currently working, I'm of course going to assume you either are or want to be interviewing in other places too. And that doesn't affect my behavior in any way. But if you tell me, I'm now wondering why you are telling me and how you're trying to manipulate me.

If you have an offer on the table, and you really want to get this other job, that's the one time you need to volunteer this info. And in doing so, you better explain that you have another offer, but you really want to work here so that's why you're interviewing. This assumes that it's true and you'd preferentially take the second job if they hurry up, but you don't want to loose the first offer if you're not going to get the second job. Note that you shouldn't reveal who the first company is nor what the offer is. And BTW, don't tell the offering company that you're still interviewing and hoping to get that other offer...

You can ask for more time and you can ask for the second company to hurry up. But be aware that neither is obligated to do so. And most will be willing to go along with any reasonable request. And there is some risk involved.

BTW, I'm pretty sure this is all covered in the podcasts.