Sometimes, you have no choice: You have to jump ship. But how do you know it's time? How do you distinguish between a work situation that is difficult but can still be repaired, and one where the best solution is to leave?

It's all a matter of knowing how to read the clues. Back in the late 1990s, it took Hattie Harvey a while to realize that she needed to leave her event-planning job at a car-rental company in order to move up the ladder in her chosen field, public relations.

At first, Ms. Harvey was mollified by her supervisor's offer to let her juggle some public-relations work with her event-planning duties. But after unsuccessfully seeking to delve more deeply into public relations, Ms. Harvey realized that the change she needed was never going to happen at her current position. To her, a telltale sign was the fact that her requests were ignored "over and over again." What's more, she says, she looked around the company and "it didn't look like anybody was going anywhere" to make room for her to move up. So, she left for a public-relations job at another unit of the car-rental company's parent.

Looking back, Ms. Harvey is glad she made the move, because it allowed her to advance in public relations, eventually leading to her current job at BankAtlantic Bancorp in Fort Lauderdale, Fla. "By making that switch, I was able to do what I wanted, which opened doors for the next job," she says.

To help determine whether you should stay at your current job, Marshall Brown, a career coach in Washington, suggests asking yourself: "Do you see yourself being there another year from now?" Also pay close attention to what those close to you have to say. Tom Welch, a career coach in Stuart, Fla., recommends that people pay heed to friends who ask, "Gee, what's wrong?" and use that as a wake-up call to reassess your job. "People may tell you that you're not the same person that you've been," he says.

Mr. Welch then proposes a four-step test to determine whether you need to leave. The first two steps consist of conducting an "inventory" of your prized skills and values, the latter category including issues such as compensation and job location, and comparing them to those aspects of your job. In the last two steps, you should ask yourself if you are "around people you appreciate being around" and "if you feel you're making a difference."

Once answers are in hand, it's time to do some analysis. "If you've got all four of the components out of whack, you're in the wrong situation," he says. But what if the report card is mixed? Mr. Welch warns that there's no one-size-fits-all answer, but that generally speaking he would rank parts one and two higher than three and four. If an employee isn't working with people he or she enjoys being with or doesn't feel that he or she is making a difference, then "you may be able to adapt."

But if one's current job flunks parts one and two of the test, then watch out. "If your skills aren't met and your values aren't met, I'd say you probably need to do something different," says Mr. Welch.

In trying to decide whether to stay or leave, keep in mind that while work may be a good way to pay the bills, an ideal job should be something you love to do. Steve Mitten, a career coach in Vancouver, British Columbia, says people should take stock of "the sense of joy and meaning" in their careers. He recommends an exercise in which you rank the joy you get from your job on a scale of one to 10. "If 10 is 'I really love this thing' and one is 'I hate this, I'm just doing it for the money,' and if you're spending a lot of time below five, that would be a great indicator that this isn't a great fit for you," says Mr. Mitten.

As you assess whether a once-promising job has run into a dead end, take a reading of your standing in the office. If something's changed for the worse, it could be a signal that it may be time to get out. "Maybe somebody is looking over your shoulder, maybe you're not getting the e-mails that everybody else is getting," says Mr. Welch.

Perhaps vendors or clients who once were in regular contact with you are now dealing with someone else. "Those are the kind of clues that would tell me, 'Something's wrong, something's changing here,'" he says.

Even after deciding that they're stuck, many employees stay at dead-end jobs because factors such as the uncertain job market keep them from leaving.

Although it's easier said than done, Mr. Welch says he doesn't think people should let fear keep them from making career or job changes. "I think it's a mistake to do that," he says, "because life is too short."