JENNA CHERNEY recently caught her daughter, Lila, red-handed: The 6-year-old was clearly responsible for spilling corn kernels all over the floor. But when Cherney asked why Lila had tried to make popcorn, “Lila told me that her dad lets her,” she says. “I almost believed her at first, but of course it wasn’t true—and I was disappointed that she had lied right to my face.”

Dishonesty is actually part of an important developmental step at this age. “Lying shows that kids realize that others don’t always see or know what they do,” says Parents advisor Eileen Kennedy-Moore, Ph.D., creator of the audio/video series Raising Emotionally and Socially Healthy Kids. However, you can still teach the value of honesty and minimize tall tales.

Encourage the truth.

As Lila did, your kid may lie to stay out of trouble. Counter this urge with a simple switch. “Don’t ask, ‘Did you do this?’ because nearly every kid will instinctively say, ‘No,’” says Dr. Kennedy-Moore. Instead, tell your child you will actually be happy if she tells the truth. Focusing on the positive can work: Research suggests that hearing about a positive response to honesty increased children’s truthfulness, while hearing about how a liar was no longer trusted did not. “Children want reinforcement from their parents for being honest, but over time they’re more likely to be truthful because they feel it’s the right thing to do,” says Victoria Talwar, Ph.D., associate professor at McGill University, in Montreal, who has led studies on kids and lying.

Accept mistakes.

It may seem counterintuitive, but when your kid tells you that he’s done something wrong, you should praise him. “Rewarding good behavior is much more effective than punishing bad behavior,” says Holly Schiffrin, Ph.D., associate professor at the University of Mary Washington, in Fredericksburg, Virginia, and coauthor of Balancing the Big Stuff: Finding Happiness in Work, Family, and Life. Simply saying “I’m so proud of you for telling the truth” will reinforce how much you appreciate honesty.

Model better behavior.

Your kid’s honesty starts with you. “Kids learn more from what we do than what we say,” notes Dr. Kennedy-Moore. White lies—like fudging your kid’s age in order to pay a cheaper admission at a theme park—definitely count. “Children are black-and-white thinkers, so if they hear a parent lie for any reason they think it must be okay,” says Dr. Kennedy-Moore. It’s also helpful to see honesty as a family expectation.

“My grandma had been poor when she found a large sum of cash in a bank bag; no one would’ve known if she’d kept it, but she turned it in to the bank and saved someone’s job,” says Dr. Kennedy-Moore. “My children grew up hearing that story, and it helped them learn that our family tries to do the right thing.”

Avoid negative consequences.

Despite your best efforts, your kid will still lie. “Children practice any new skill when they first develop it,” says Dr. Schiffrin. Penalizing your child for lying may make her more likely to repeat the behavior in the future, so avoid the temptation to immediately freak out. Dr. Talwar explains that people most often lie when they think the benefits of dishonesty outweigh those of telling the truth—and your child is practically hardwired to keep herself out of trouble.

A smarter tactic: “Ask your child, ‘What could you have done differently?’ and then help her fix the situation,” says Dr. Schiffrin. If, for example, she wrote on a wall, have her clean the marks. Above all, says Dr. Schiffrin: “You want to help her understand why lying isn’t okay and teach her a better response.”