Julia has never been especially fearful, so I was caught off guard when just before her fifth birthday she became terrified of being poisoned. She cried after she accidentally swallowed a crayon shaving. Even the beloved cherry-red lipsticks that were her favorite part of dress-up now seemed fraught with danger. "Mommy! By mistake lipstick got on my tongue!" she yelled, running into my room one day. "Am I going to die?"

Like any conscientious mom, I explained to Julia that most things are kid-safe. I showed her the word "nontoxic" on crayon boxes. I tried to convey to my distraught preschooler in every way I could think of that she just wasn't going to be poisoned.

But in my heart of hearts I blamed myself. Had my constant reminders about putting things in her mouth pushed Julia into some sort of phobia? Thankfully, before I had a chance to press the "I'm a Lousy Mommy" button, something happened: Her fear disappeared. Like a summer thunderstorm, it blew over as quickly as it had moved in.

I still don't know exactly what caused Julia's fright; nothing bad had happened to ignite it. But I did find out that fears are a natural part of how kids learn to understand their environment, according to John Piacentini, Ph.D., director of the Childhood OCD, Anxiety and Tic Disorders Program at the University of California, Los Angeles. Every developmental passage, from infancy on, is accompanied by some kind of anxiety, ranging from monsters to vacuum cleaners. "What seems logical to us isn't always to a child," he says.

Whatever the source of your little one's fear, it's how you help her confront it that's key.

Jeanne McDowell is a Los Angeles correspondent for Time.

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