Dear Mr. Dad: Our 9-year-old son is a habitual liar. He fibs even about the smallest, most insignificant things. But whenever we challenge him, he stands his ground and tries to convince us he’s telling the truth. What can we do?

A: Before we get to the what-you-can-do part, we need to find out what’s going on and why. Children lie for a number of different reasons, primarily to impress others, boost their self-esteem, feel less insecure, or avoid punishment. (Hmmm. The same reasons many adults lie, too.)

For example, your son might be bragging to his friends about all the latest games he has in his room—even though you can’t afford any of them. He may figure that if he told the truth, nobody would be interested in him. If he’s feeling especially insecure, he might spin some incredible yarns about his talents or abilities to help him feel better about himself.

The real biggie, though, is fear of punishment. No matter how trivial the original “offense” might be—maybe he broke one of your Ming vases playing ball in the living room, or he didn’t do his homework—a child’s natural self-defense mechanism is to lie about it. (“Me? I didn’t break it—it was Spot,” or “Yes I did do my homework, but Spot ate it before he knocked over the vase.)

As a parent, your natural inclination is probably to punish your son. After all, at nine, he’s plenty old enough to know that lying is wrong. But before you do, ask yourself why he feels he can’t be truthful. Understanding that will probably produce better results than grounding him or taking away privileges.

For example, if you think he’s lying to impress others because he’s insecure or doesn’t feel good about himself, punishing him for having those feelings will just make him less likely to talk to you—or anyone else—about them. Which means he’ll never get the help he needs.

If he fibs to avoid punishment, could it be because your disciplinary measures are too strict (at least in your son’s mind). Sit down—at a calm moment, not right after you’ve caught him in a lie—and ask what he’s really afraid of. If his explanations make sense, work with him to come up with better consequences. Not too lenient, but not so stringent that he has to lie to cover his tracks.

Now’s also a good time to talk about why honesty is important. Trust (in my book) is the most important quality in any relationship, personal or professional. Give him examples of people you know (or hear about on the news) who are successful and respected because of their honesty. Then list a few whose lives have been negatively affected by lying or cheating (another form of lying). Think Tiger Woods and Barry Bonds.

Another time, you may want to talk about some situations when, despite the general rule of honesty being the best policy, it’s appropriate to stretch the truth (aka telling “little white lies” or “words of kindness.”) Sometimes being honest can hurt other people’s feelings, so we want to spare them pain or embarrassment by circumventing the truth (this goes beyond, “do these jeans make me look fat.”) Have him come up with some examples on his own, and talk about the difference between lying to protect yourself, and hiding the truth to be kind and sensitive to others. Admittedly, it’s a thin and not-always-clear line, but hopefully, as your son grows, he’ll learn to distinguish both sides of that line.