Donna developed an eye for fashion when she was just a toddler in day care. "She would actually say, 'So-and-so has this skirt. Can I get it?"' says her mother, Christie Rickert of Locust Grove, Ga.

But since Ms. Rickert enrolled Donna, now 4, at ABC Montessori School in McDonough, Ga., where all the children wear uniforms, "we don't have those kinds of conversations anymore," she says. Putting on her white or navy polo shirt and navy or khaki shorts or skirts, just like all the other kids, "took the pressure off, of trying to belong."

A growing number of preschools and child-care centers are requiring children to wear uniforms. Many parents like the ease of dressing children in uniforms and say it usually costs less than other clothing. Day-care directors say uniforms lend an atmosphere of professionalism, giving a sense of order and security.

At ABC Montessori, where Ms. Rickert's daughter Donna is enrolled, Kimberly Morey, executive director, says having the children wear uniforms "eliminates distractions.

"Children come in comfortable and prepared to focus. They're not worried about what their neighbor is wearing or what their mom didn't let them wear today," Ms. Morey says. Uniforms reinforce feeling part of a group for children, she says. Even in preschool, "if you put a blue shirt on a child, he or she knows 'I'm getting ready for school.' "

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