What to Know: When a child is upset, they can't take in large amounts of information, says Sheehan. Which is why throwing your own grown-up tantrum in response to his miniature one never works.
What to Do: Speak in a calm, commanding tone of voice and keep your words simple and straightforward (think "you need to stop," or "no hitting"). Save the big, lesson-imparting "discussion" for later. At that point, you can talk about the rules -- "It's never okay to hit" -- and brainstorm other ideas for what your child can do when he's angry, such as say the words "I am angry!" or hit a pillow. Even if your child doesn't understand all of this, starting the conversation now will help him express his feeling more clearly in a year or two.