At 3, Kate Schwarz of Rockville Centre, NY, developed an intense fear of any character in a costume. During her cousin's party at Chuck E. Cheese, she stood on her chair and shrieked so loudly at the sight of a costumed mouse that the party came to a stop, says her mom, Lisa Bain. She and Kate had to eat their pizza in another room.

Babies and young toddlers live life in the moment and are easily distracted from something unpleasant. But between 2 and 3, your child will start to fret over little worries.

"At about 2, kids are beginning to develop their imaginations, opening up a whole new world," says Claire Lerner, director of parenting resources at Zero to Three, a child-development nonprofit in Washington, DC. "But fears come with that, because they're still struggling to distinguish between reality and fantasy."

Nearly anything can frighten a child at this stage—monsters, animals, loud noises, even the bathtub. Some frights will pass in a few days, while others can persist for a year or more. In the meantime, here's how to calm your child:

Treat his fear seriously. Let him know that it's okay to be scared. Try saying, "That big mouse showed up and scared you. You didn't like that."
Take the lead. Do something that shows he can feel safe taking a chance, like hugging the character yourself.
Build him up. Fear is all about loss of control, so help him get it back by talking to him about what he can do that will make him feel less frightened.
Practice, practice, practice. Gently persuade him to take tiny steps: Maybe he can just stand near the character and wave. Each step will boost his confidence and make the next step even easier.

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