When your 1-year-old shouts "No!" and throws his spoonful of cereal on the floor, take his act of rebellion as a sign you're doing something right, says Theodore Dix, a developmental psychologist at the University of Texas at Austin. His research has found that defiance between ages 1 and 2 is linked to positive parenting strategies, like giving children some autonomy and being sensitive to their needs. Early defiance even appears to correlate with high scores on cognitive tests. That may be because when young children feel very secure, they're more willing to test the limits and explore the ways the world works, he adds. "I like to think of it as these kids becoming empowered."

Dealing with a pre-pre-pre-teen So your toddler is resisting your efforts to put on her shoes or get her strapped into the car seat -- again. Instead of taking it personally, try to have patience, and instruct her about what is appropriate and what isn't. For the car-seat rebel, you'll put her in anyway and say something like, "I know you don't want to get in, but you have to because it keeps you safe." Use a calm, assertive voice, and repeat yourself as many times as necessary until your message sinks in.

Lisa Guernsey is the author of Into the Minds of Babes: How Screen Time Affects Children From Birth to Age 5.