Shampoo savvy
Babies: Washing hair once or twice a week is usually enough. If your baby has cradle cap, which (despite the flakes) is an oily-skin condition, wash with a dandruff shampoo two or three times a week after massaging a little olive or baby oil onto his scalp to loosen the flakes, says Ari Brown, M.D., a pediatrician and coauthor of Baby 411.
Toddlers: Three times a week is fine (more often if he's got a penchant for mashing bananas on his head).
Preschoolers and up: As your child's hair gets longer, wash it every other day (less often for very curly, dry, or African-American hair; in these cases, you can use conditioner once a week, too).
At any age: Always shampoo at the end of the bath so your child's not sitting in the sudsy water, which could irritate sensitive skin.
What's the difference between baby shampoo and regular?
Adult shampoos contain chemicals called anionics (most common: ammonium laurel sulfate) that create the rich lather that most people want, to feel the shampoo is cleaning well. These can be very drying, but since adults use conditioner and other styling products and have oilier skin than kids, it's not really an issue. And while baby shampoos may claim to be tear-free, avoid getting any shampoo in kids' eyes, since even the baby kind can sting.
Here's a clip of Parenting's Lisa Bain and stylist Jennifer Bilek talking about kid hair care on The Today Show.