One way to think of this is take a look back at the previous positions you've held, then left. Did any of those companies go out of business because you left?

One way to think of this is take a look back at the previous positions you've held, then left. Did any of those companies go out of business because you left? Were they (or the department) seriously injured? Now, ask yourself if they knew they would have major issues to overcome if you left. If they didn't, then even if they fell apart when you departed, then there was nothing stopping them from laying you off if a strong enough reason came about. If, however, they realized how bad things would be if you were gone, then they were negligent by not hiring redundancy. What you need to do is make yourself as valuable to the company as you are willing to do (avoid burning yourself out though). Make sure you have a deep enough emergency fund, and enough expenses that you can cut to survive an extended unemployment. Chances are that if you are part of a mass layoff, that won't reflect as badly on you as if you got fired for other reasons. And if there is a severance package, don't panic right away -- you have time to address the situation properly. Oh, and if you have enough time off before you land your next position, make sure you take care of yourself. The lack of work stress will do wonders to re-energize you, making you perform at a higher level at the next gig and hopefully exceed expectations (thereby setting you up for promotions etc).