career path - What is a non-tenure-track assistant professor position in the USA and is it harmful?

I see some offers on the Chronicle jobs website (such as this one from UC San Diego) for non-tenure-track assistant professor positions.

Is the work of a non-tenure-track assistant professor exactly the same as the work of a tenure-track assistant professor, e.g. in terms of teaching/research ratio?

Also, would taking on a position of this type be more, less or equally helpful compared to, say, taking up another postdoc, for someone that would later want to apply to a tenure-track position?

Forgive me if this question does not make sense to you, but I have taken the impression from some sources that whatever professional decision one takes that is slightly outside the "normal" progression of an academic career can be harmful.

Answer

The most important point is that jobs vary significantly by discipline. If you are in the field of Cognitive Science, or in a related field, you are in a better position to know what a job ad in that area is actually looking for. Unfortunately, the job ad linked in the question is written in a way to make it hard for those outside the area to know what it wants - it does not directly say whether they are looking for research or teaching. There is no way to tell without asking what the teaching/research ratio would be.

In general, there are two common uses of non-tenure-track "Assistant Professor" positions in the U.S.:

1. 
   
   

   Postdoctoral positions. These are not usually considered "harmful" to your career. In many fields they are a standard part of the academic job progression.

   
   


2. 
   

   Teaching-oriented positions for which the candidate has a PhD. These may be full-time positions (as in the linked ad) or part-time.

   
   

The second type of position could be helpful, or harmful, depending on what sort of tenure-track position you are looking for. You have already narrowed down the type of institution where you would like to have a tenure-track position, and started honing your CV to be a perfect fit for that type of school, right?

• 
  

  If your type of school is an elite research school, then another postdoc seems more likely to be helpful than a teaching position. This is the type of school where leaving the standard progression is most likely to be harmful to tenure-track chances. If you are a likely candidate for this type of position, you probably know it already.

  
  
  


• 
  

  If you are looking at non-elite public universities, which have more of a balance between research and teaching, a single non-tenure-track teaching assistant professorship is not a mark of certain doom for your tenure track hopes. You can use the job to hone your teaching, move your research forward a little, and you can use the time to apply for tenure track jobs.

  
  


• 
  

  If you are looking at teaching-first institutions, or at community colleges, then you need to make sure you have excellent teaching credentials. You might be able to use a teaching-oriented term position as a way to do that.

  
  

Unfortunately, because of the excess of candidates relative to the number of tenure-track positions in many (most?) fields, and because the number of tenure-track jobs is not increasing, many academics work multiple term positions in a row. This is especially common in the humanities, and it can be "harmful" for tenure track hopes, unfortunately. I was fortunate to find a tenure-track position, so I can't speak too much to how to handle the situation of multiple term teaching positions, but you can find a lot of discussion about it on the web.