Leslie Walden's daughter Kennedy will turn 5 in October, which makes her eligible to start kindergarten. But the school year will begin without her.

Kennedy is a bright and enthusiastic child, her preschool teacher said — but she wasn't quite mature enough for the private-school kindergarten Walden and her husband had been considering. That assessment echoed Walden's motherly instincts.

"I personally felt like [she] is better off being the oldest kid in the group rather than trying to catch up," said Walden, an attorney who lives in Playa Vista.

And she's not alone. With schools' increasing emphasis on academic achievement and standardized tests and society's growing attentiveness to kids' emotional needs, more parents are considering the same question: Should they enroll their children in kindergarten, even if they feel they're not ready?

Many are making the same choice as Walden. According to the National Center for Education Statistics, among children born in 2001, 16.4% started kindergarten at age 6 or older. In 1993, only 9% of incoming kindergartners had already passed their 6th birthday.

The practice of delaying the start of kindergarten is called redshirting, a term borrowed from college sports. In that context, it refers to keeping athletes off the field for a year to give them time to grow and develop their skills, or to recover from injury.

When it comes to redshirting kindergartners, some parents' main concerns have to do with academic readiness. For others, it's about emotional development. Still more worry that if their child is the youngest in class, they'll always lag behind their peers.

And some, like Nicole Downey, remember their experiences in school. As one of the youngest in her grade, the kids around her seemed to grow up fast. "I was sleeping with a teddy bear and my friends were drinking beer and kissing boys," she said.

When it came time to enroll her two children in school, Downey, who is now a child psychologist in Tarzana, chose to hold both of them back a year.

"I was more concerned with what happens when they are teens," she said, "being mature socially and being able to make certain decisions."

As parents grapple with the question of what to do with their kindergarten-age kids, experts in early childhood education have yet to offer any clear answers.

"There is no easy metric," said Sharon Lynn Kagan, co-director of the National Center for Children and Families at Teachers College in New York, "nor should there be."

Research has shown benefits and drawbacks to holding back children. A 2006 study published in the Economics of Education Review looked at the age at which children started kindergarten and their test scores in reading and math during the first two years of school. The study found that children who entered kindergarten later had significantly better scores in those two subjects, and the advantage increased slightly by the time they were done with first grade.

But another study documented some of the difficulties encountered by children who are older than their classmates. The 1997 report, published in the journal Pediatrics, focused on more than 9,000 students ages 7 to 17. Researchers discovered that those who entered school later were more likely to have behavioral problems.

Despite the conflicting data, parents may be comforted to know that the age at which a child enters kindergarten quite possibly makes little difference in the long run. Younger children might struggle a bit with kindergarten tasks, and older children might do well, but according to a paper published by the Society for Research in Child Development, most of those distinctions vanish sometime in elementary school.

"Any effects that people have seen — whether they are positive or negative — seem to fade over time," said Kyle Snow, the director of the National Assn. for the Education of Young Children's Center for Applied Research. "Even by third grade, they seem to have been pretty wiped out for most kids."

That kind of even-keeled approach — that the kids will be all right — led Kara Tome to enroll her daughter Avery in kindergarten even though she turned 5 at the end of July, putting her on the younger end of the spectrum. Tome, an art curator and writer in Burbank, thought that the outgoing girl would fit in with her classmates just fine.

"She is a bit mature socially, and she is very articulate," Tome said. But she added that if Avery had been more shy and reserved, she may have considered holding her back: "I can understand how that would be a little more nerve-racking."

When assessing a child's readiness for kindergarten, education experts focus on five primary areas, Kagan said: physical well-being and motor skills, social and emotional development, language skills, approaches to learning, and cognition.

But children don't develop at the same rate in all five areas, and being behind in one of them doesn't mean they aren't ready to enter school, according to Kagan.

Experts continue to debate which of these skills is most important in deciding whether a child should start kindergarten.

"Five years ago it was all about literacy and getting kids to read," Snow said. "Now we are in a mode that focuses on social and emotional functioning."

Concerns about emotional development helped persuade Molly Murphy to give her daughter Elizabeth an additional year in preschool, even though she turned 5 last September.

"She had friends going to kindergarten last year, and they separated from their mothers more easily," said Murphy, an attorney in Los Angeles. "She would have been really overwhelmed, and I'm afraid it would have taken more time to undo that damage. … I think she will have a lot more confidence being older."

Educators agree that social skills can be just as important as academic skills. In a study published by the National Center for Education Statistics in 1995, kindergarten teachers said that being able to recite the alphabet or count to 20 was impressive but less important than being able to communicate one's needs, share with others or show enthusiasm and curiosity for new activities.

Children who aren't socially or emotionally prepared may struggle at times, and being held back for a year can enable them to grow in ways that can't be taught, said Christine Friedman, who teachers kindergarten at Sinai Akiba Academy in West Los Angeles.

"Kids need to have experiences in order to understand how to relate to people, how to have conflict and resolve it, how to share," she said. If children are lacking those experiences, it can lead to problems in the classroom.

Even so, considering that children's development is individual, Kagan favors putting kids into kindergarten as soon as the law says they are old enough to be there. Being in school, she said, provides children with rich opportunities to learn and grow — not to mention the fact that the cost of daycare or preschool precludes some parents from even having a choice.

"I am a strong opponent of this notion of keeping kids out until they are 'ready,'" she said. "All children present different readiness profiles — there is not one profile."