TITLE: Can breadth hurt a job candidate?
QUESTION [28 upvotes]: I am a junior mathematician, currently on the job market. I have been involved in a number of projects spread over several very different topics of mathematics, some being very mathematical projects that appeared in computer science theory forums (I do not consider TCS my specialty). 
I had thought that breadth would make me an appealing job candidate (if I work in two areas, I can apply to jobs listed in both!). However, it was recently mentioned to me that this might be viewed negatively as 'lack of focus' and even hurt my job prospects. Another criticism I have heard is that a research group in area X might be reluctant to hire me out of fear that I'm really more interested in area Y. I have been most troubled by recently witnessing a member of the hiring committee at my current university demonstrated a complete ignorance of TCS forums (i.e. not knowing what FOCS is). I assume this means that this individual would value such publications negligibly at best (in contrast, I'd expect/hope that he would be able to identify the a top journal in an area of math outside his expertise).
Can any mathoverflowers either confirm or dispel these concerns? How do committees evaluate candidates with work in multiple areas (and/or reaching into other fields)? I am also interested in hearing how others have marketed themselves in similar situations.

REPLY [12 votes]: The majority of answers have suggested that breadth doesn't hurt you, but I have a more pessimistic view, based on my personal experience.  I find that it is quite common for people to judge your research ability by what they consider to be your best piece of work.  So if you're faced with the choice between
focusing on a single area, and publishing two papers in that area, one mediocre and one outstanding; versus
working in two different areas, and publishing one good paper in each area,
then my belief is that you will usually be perceived to be a better researcher in the former case.  Now, it's true that the above dichotomy may be a false one.  Perhaps your skills and temperament are such that if you choose to focus in just one area, you get bored and can't produce any good papers.  But to the extent that you are faced with that choice, then I think choosing to focus on producing one really outstanding piece of work will generally be better for your reputation as a researcher.
Having said that, I don't necessarily advocate shunning breadth (again, assuming you actually have a choice).  First of all, as others have pointed out, depending on what job you're after, your perceived status as a researcher may not be the most important factor.  Secondly, in the long run you are almost certainly better off working on things you're interested in, rather than pursuing things that you think will impress other people.  Of course, some compromise may be necessary since you do need to find employment somehow.  But if your natural temperament inclines towards breadth, then ultimately I think you'll be more productive if you pursue your natural inclinations instead of forcing yourself to specialize in a way that you find distasteful.  One advantage of breadth is that you have a good chance of finding connections between areas that specialists would never have seen.  It may take you a longer time to produce that outstanding paper, but it could very well end up being even more outstanding than any paper you could have published quickly by specializing.