When leaving your job, it's advisable to give your employer a two week advance notice. While this meets minimum standards, it doesn't usually allow time to find a replacement. So if your departure is amicable, and you can spare the time, it doesn't hurt to give the employer a little more notice. Want to score some really big points? Help find, or train, your replacement. Then again, you may not have this option. The employer may get upset, and ask you to leave sooner, even immediately. Maybe your work situation is so intolerable, you can't stand to wait any longer. Or perhaps the people at your new job need you right away. Each situation will be different, so use your judgement. Just remember, in the business world, it's never a good idea to burn bridges. You and a former boss could turn up at the same company in the future. Plus, you want to be reasonably sure you can get a good reference. So try to be professional about leaving, and do what you can to make the transition easier for everyone.