When my son Henry and his cousin Brian were 4, Brian would often go missing at family gatherings. Not really missing, of course. But we'd all be eating or talking or chasing after kids, and someone would ask, "Where's Brian?" When we'd look around, he'd always be right there, quietly and happily entertaining himself with a Matchbox car or some other toy he'd found.

Henry, though, never got lost. He preferred constant interaction  -- if he was working on a puzzle, for instance, he wanted me to be sitting right there, handing him the pieces. He wouldn't have been tempted to play by himself if he'd had 50 Matchbox cars.

It's not that I minded building towers or zooming cars or playing Trouble with him day after day. It's just that occasionally I wouldn't have minded being able to read more than the headlines in the morning paper before Henry called me to my next activity.

As it turns out, it would have been better for Henry, too, if he could have managed without me for a Lego project or two. Playing alone is good for a child  -- for his self-esteem, his imagination, and his ability to make it in the wider world, where Mom or Dad won't come running to amuse him every time he's bored, says Melanie Killen, Ph.D., associate director of the Center for Children, Relationships and Culture at the University of Maryland. Good news: There's hope for me and other parents of kids who haven't come prepackaged with the "I love independent play" ingredient. What you can do, early on and as your child grows, to encourage this behavior:

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