A few months ago I chatted with my mother on the phone, relaying all the wonderful things my 3-year-old could do. "You should see this, Mom," I glowed. "He already writes the letters of the alphabet. He counts like crazy, and his vocabulary is unbelievable."

"Don't you think he should be in preschool?" was my mother's reply.

Preschool. I hadn't really given it much thought. He was about the right age. He absorbed information like a sponge. But for the past three years he had spent all day with me. And although he had a few friends, he had never participated in a group activity.

Maybe my son was ready for preschool. Still, I wished there was a way to know for sure.

Each year, education experts see children from age 2 to 4 enter preschools around the nation. "The average preschooler that I see in the schools is probably of age 4," says Mary Nesset, a certified school psychologist in Michigan.

But don't rush your 4-year-old out the door just yet: Children reach developmental milestones at very different rates. Here's how you can determine if your child is ready or not.

Cognitive Development
Somewhere between birth and age 3 a child develops the ability to use language. According to Joanne Kathy Estes, an early childhood educator in Mississippi, "A child needs to be able to express his physical and emotional needs to the teacher or parent in very simple language."

Estes also points out other cognitive skills that prove useful to the preschooler. "[The child should have] an attention span long enough to listen to a five-minute story [and the ability to] follow simple one-step directions."

When Jessica Little's daughter, Meghan, started preschool at 3 1/2 years old, she had no doubt in her mind that her child was ready. "Meghan actually asked me when she could go to school," recalls Little, of Pennsylvania. "I had her input the entire time. She even picked the school she liked the best. I guess I just followed her lead."

Physical Development
Following your child's lead is also the trend in toilet training. In fact, most experts agree that forcing a child onto the toilet by a certain age is not only unnecessary, it can actually stall a child's development. As a result, many 3-year-olds are very happy to be wearing diapers. Unfortunately, many preschools require a child to be 100 percent out of diapers before the first day of class.

Physically, the child must be ready to care for his own toileting needs. Teachers will help out with the occasional stubborn button or zipper, but all in all, the child should be as self-sufficient as possible. "A child needs to be able to take care of his basic needs," says Estes. "[This includes] potty training, manipulating most clothing and washing hands."

Social Development
While a child's first introduction to socialization may come at home with siblings, successful interaction with peers is critical to preschool adjustment. "A child who is ready for preschool will usually be interested in other children," says Estes. "He may not be ready for group play, but partner play is usually appropriate." A feeling of belonging to the group is an essential ingredient in a child's preschool experience.

This rang true for Jeannie Kouch of Wisconsin, and her daughter, Anna. "She is the oldest of three children. She was great with the newborn, and even better with her 2-year-old brother," Kouch says. "I was shocked when the teacher said Anna wasn't getting involved with the other children. When she took a more active role, she really started to like preschool."

Emotional Development
You can breathe a sigh of relief once your child has been potty trained and can function well in group situations, right? Not so fast, say experts. "I feel that it is never intellectual [development] but emotional that determines a child's readiness," says Toni Healey, a preschool program director near Washington, D.C. "A child [should] separate well from the parent. If a child is continually crying the entire time he is at preschool, then he is not ready."

Parents need to be honest with themselves about their child's emotional strengths and weaknesses. "If the child is very fearful in new situations, he is probably not ready to be cooperative in a school situation," says Nesset. "He has to be at a developmental level of being able to tolerate being away from Mom before he will be amenable to outside influences."

As a result, a child with extreme separation issues may not find preschool to be advantageous. Nesset points out that spending time at home with a caring parent who exposes the child to educational and social opportunities might be the better course of action.

Trial and Error
After all is said and done, you still may be wondering if your child is ready for preschool. In this case, you might never know unless you try. If you decide to take a "trial and error" approach, be on the lookout for signs that your child is not adjusting. "An obvious clue would be if the child is reluctant or crying when it's time to go to school," says Nesset. She stresses that during the initial period of adjustment, some tears will be normal.

A good rule of thumb, according to Joanne Kathy Estes: "If the child has not mastered the basic group routine in one to two months, he may not be ready to participate in a preschool program."