About 6 Months: Undiscriminating Smile
While all babies develop at their own pace -- and some babies are just a lot more smiley than others -- midway into your child's first year, she'll most likely be a smiling expert. "Six-month-old babies grin at you no matter what you do," says Dr. Cowan.
Your child may also start smiling at everyone else around her when she sees that it gets a response. At the same time, her grins are becoming more meaningful. She might smile because she's learned a new skill -- or because she's glad to see you. "Your child is developing memory, so her pleasure may be greater when she sees you because she's aware that you were gone," says Dr. Renna.