When Do Babies Laugh?

Somewhere around 4-5 months, your baby will enter that magical stage of laughing. In the first few weeks of life, infants express needs that demand immediate gratification—most notably for milk, sleep, or a cuddle. But it's often not until that first smile, when they're between 6 and 12 weeks old, that we realize babies want social interaction as well.

The smiles express that they're happy, content, and enjoying what's going on around them. Soon enough, though, smiling turns into laughter. Here's when to expect your baby's first laugh, with tips for encouraging the developmental milestone.

When Do Babies Start Laughing?

Every child reaches milestones at a different time, but you can expect your baby's first laugh around 3 or 4 months. Full-out belly laughs might appear around 5 months of age.

Once your baby masters smiling, they will start to realize that those smiles bring positive reactions from well, everyone. Your baby will probably start adding sound effects, such as cooing, to their gummy grins, according to Mark Gettleman, M.D., a pediatrician and owner of Dr. Goofy Gettwell Pediatrics in Scottsdale, Arizona. Cooing will turn into small giggles, and eventually your baby will laugh out loud.

What Makes Babies Laugh?

Most experts agree that the root of humor is taking something in its familiar form and turning it upside down or making it offbeat. That's why very young babies really don't have a sense of humor—they're still learning how the world looks, feels, and sounds in an ordinary context, so they don't "get the joke" when something's out of whack. Hence, a baby's first peals of laughter (around 3 or 4 months) tend to be a response to stimuli. A ride on a bouncing knee, for instance, gets a laugh because it's physically stimulating.

But just a few months later, funny sounds coming from a toy will evoke a smile or a laugh. Starting around the 6-month mark, babies have enough information about the world around them to be surprised —and delighted—at the unexpected. "Infants experience pleasure from processing information that's a little bit new and a little bit similar," says Paul E. McGhee, PhD, a developmental psychologist and author of Understanding and Promoting the Development of Children's Humor. Peekaboo becomes a funny-bone favorite now, and almost anything that is decidedly out of their ordinary realm of experience gives kids the giggles.

How to Encourage Baby’s First Laugh

A baby's first laugh usually begins with parents making faces and funny noises to get the baby excited and interested, notes Doris Bergen, PhD, a professor of educational psychology at Miami University in Oxford, Ohio. A baby's relationship to the adult doing the funny stuff matters as much as the physical sensations and funny noises; they will laugh and play only if they feels secure.

After the first few chuckles, what makes an infant giggle is primarily physical and feels pleasurable: blowing raspberries on their belly, tickling your baby's feet, picking them up and flying them gently through space. At about 4 months, a baby begins to laugh at things they can see and hear. Your baby will delight in nonsense humor —an exaggeration of things they typically experience, such as faces with wide-open mouths and big eyes and wacky sounds such as toots and trills.

Your baby's giggles mean that they are having a good time, but they don't yet have a true sense of humor. They will begin to develop one within the next six months, when they have the cognitive ability to find an idea funny.

When Do Babies Become Ticklish?

Try to tickle your newborn, and you'll discover that they won't laugh. Why aren't newborns ticklish? Well, doctors aren't entirely sure. One theory is that newborns aren't ticklish because they don't yet understand that other people are separate from them, says child development expert Lawrence Kutner, PhD, co-director of the Harvard Medical School Center for Mental Health and Media.

If you've ever tried to tickle yourself, you know it doesn't work. "But within the first few months, babies become ticklish, so one theory is that this may be a marker of the child realizing that other people are separate from them," says Kutner. However, he adds, we can't confirm this because for obvious reasons, you can't exactly interview a newborn to ask them. Fair enough.