I recently had the opportunity to talk with a fifth year associate at a big NY law firm.  He seemed to be doing a lot of the right things and it occurred to me that others similarly situated may have the same questions.  Here are some quick thoughts:

1. Ask questions.  I think it is appropriate at the end of your fourth year or beginning of your fifth year to ask the following question:  “What types of things should I be doing this year and the years ahead to prepare myself for consideration for admission to the partnership.”  The answer you receive may be very revealing.  The answer may provide some clues as to timing and whether partnership track is a realistic possibility for you.  I think the question is appropriate if phrased in this (or similar) manner (i.e., using the word “consideration,” softens the question and shows that you do not assume you will be automatically admitted).
2. Listen to what is said and what is not said.  Obviously, context and facts and circumstances are important but generally, my view is that I would be leary of a response that you are doing everything right and there is nothing significant you can be doing at this time or it is too early to think about that.  You are looking for specific actions you can take and some sort of confirmation that there is a real possibility you will be considered for partner.  Otherwise, you may want to think about jumping firms because starting next year it may be too late for you.
3. Transition from junior associate to mid-level associate by taking on more firm responsibility.  Along with producing good work and keeping billable hours up, start taking on more firm responsibility.  Head up your firm’s associate committee, become a summer associate mentor, ask if you can supervisor younger associates on projects, speak and write more, ask for more opportunities to represent your firm at firm functions, get more involved with the billing process with clients for whom you work (i.e., evaluate whether your time spent was appropriate, perform similar review for other associates time, become the point person with the client to deal with billing questions, disputes, and write-offs).