come in with their families, it has become a power struggle," explained Dr. Alison Schonwald, a pediatrician who supervises the "poop school," as it's affectionately called by staffers. "The kids kind of dig in their heels and put a line in the sand." Health Minute: Watch more on the perils of potty training »

The American Academy of Pediatrics reports that most children show signs they're ready to potty train between 18 and 24 months. Doctors suggest a child may be ready to start trying if he's staying dry for at least two hours at a time during the day, walking to and from the bathroom, asking for a diaper change and asking to use the potty.

For some kids, the toilet training process can take more than a year,or longer.

The six-week program at Children's Hospital is one of a handful around the country. Kimberly Dunn, a pediatric nurse practitioner, has worked with some of the 450 young graduates over the years.

She said most of the kids admit they are afraid to use a toilet. "Oftentimes, the parents come in and they want to know why they're afraid," Dunn said. "You could ask the kids until they're blue in the face and you hardly ever find out why."

Dunn meets with a half-dozen children once a week. She uses books, music and art to help the students overcome their fear of using the toilet. She helps them set small, realistic goals. For instance, she said, week one involved just sitting on the toilet for five minutes. She encourages