The longest acceptable temporary assignment is 6 months -- the only legitimate exceptions to this rule are contracts tied tospecial projects that have a definite completion date (may be as long as a year or two, but definitely will end according to aformal schedule). Six months is a sufficiently long trial period for any company to decide if they want to hire an individualpermanently. If the position deals with daily operations and the contract term is longer than six months, there is a goodchance that the company is abusing contract positions to avoid paying benefits or to play accounting games (it makes payrollcosts appear smaller). Odds are good this company will abuse you in other ways as well, so it is best to avoid thementirely. Walk away quickly and don't look back if both the term is longer than six months and the rate of pay is belowaverage for the type of work -- you have encountered a sweat shop that uses contracts to lock in employees because theyhave a serious retention problem.
Another thing to be very skeptical about is companies that end your contract, but promise to rehire you a month or two later"when we get into the next fiscal quarter" or "we need you in another department." Don't wait, and don't be overly flatteredby statements like "we don't want to lose you" or overly influenced by promises of a direct-hire later "if you just hang in withus a little longer." Chances are they won't recall you; their budget is blown and the manager doesn't know what he or she isgoing to do about it and is hoping for a miracle. In the meanwhile, you've lost a month or two of critical job-hunting time. And don't believe that the size or reputation of the company makes any such promise an iron-clad guarantee, no matter whatthey make it sound like. I had a Fortune 100 company that had otherwise treated me very well keep me on hold for threemonths by using the phrases mentioned above, and they never recalled me! Their budget crisis was real, but that was noexcuse for making promises they could not keep.
The best way to protect yourself from employers who would abuse the system is to establish a good relationship with youragency recruiters (you should always have more than one agency looking for jobs for you), and let them know that you donot want to consider assignments that last more than six months unless the assignment is clearly identified as special projectwork. They know what I just explained in the previous two paragraphs, and will help you out.
There's also the question of what to do if you have completed the initial contract term and the company wants to extend yourcontract rather than hire you directly. This decision really has to be made on a case-by-case basis, as there are too manyfactors that may be involved to give a stock answer. In one case, I accepted a six-month extension for a position I reallyliked (and rearranged my life for it), only to be laid off after one more month due to budget cuts -- this was not onlyinconvenient and a nasty surprise for me, I also turned down a direct-hire opportunity I received two days after acceptingthe contract extension. In another case, I completed a one-month "emergency" contract -- and did an absolutely outstandingjob of hauling the company's bacon out of the fire. When the company offered to extend my contract rather than to hire medirectly after I had gone well above the call of duty and proved my value beyond a shadow of a doubt, I knew they wouldnever value me properly, so I turned down the extension and moved on. (The company went out of business nine monthslater -- they were hiding financial problems by using contractors to make payroll appear smaller than it was.)
Contract jobs allow you to gain new experience, often pay more than direct-hire positions, and are almost always moreflexible about letting you take time off to go to interviews (and you almost never need to lie about why you need to leaveearly or take a long lunch!). If you behave as a consultant (as opposed to a "temp"), you can sometimes even manage towork flex-time or at home (but be sure you get your work done -- don't mess the rest of us up!). If can do without benefitsand don't mind switching jobs every few months, contract work makes it a lot easier to look for your dream job.
Oh, one last note -- if you are anything above entry-level, don't call it "temping" on your resume -- call it "contracting." Itsounds more professional and puts a more positive spin on it, even if you really did just take the job to pay your bills.
I've "temped" on and off for more than 15 years, and I think that staying actively working -- whether in a "permanent" (youmean there's such a thing?!) job or a contact job -- looks better to potential employers on your resume. In fact, I entercontract jobs on my resume exactly as I do direct-hire jobs, I just put (contract) after the job title to explain why the jobonly lasted a few months, and "contract ended" at the end of the description where I usually put "laid off due tocompany-wide reorganization." (I have to enter this information because I have been caught in lay offs so many times itlooks like I'm unstable or job-hopping when I'm not -- just unlucky.) But there's a lot more to the decision about how longto temp than just whether it will affect one's ability to get a direct-hire job.