Childhood, that fantastic fraud that adults inflict upon children in the name of good intentions, education, the future, citizenship and morality, had glory days between 1945 and 1968.

Starting today, that glory is being explored at the National Museum of American History in an unsettling little show called "This Is Your Childhood, Charlie Brown -- Childhood and American Culture, 1945-1968."

In those years of baby boom, children under 14 went from being a quarter to a third of the American population. They were an indispensable part of the new suburban culture that had its own architecture not just in ranch houses but in the family rooms inside them -- one is reproduced in the show with a 1950s coffee table shaped like an artist's palette and a massive television in a bleached maple cabinet. (Is anything more old-fashioned than yesterday's Look of Tomorrow?)

Better Homes and Gardens said in 1954: "The foundations of democracy are built most firmly within the home. In a country whose children have learned these lessons well, there need be no fear of dictatorship overcoming democracy."

A child in a cartoon drawn by Charles Schulz in his pre-Charlie Brown days says: "My buddy and I like to think of ourselves as being successful products of the new post-war world."

The "Peanuts" cartoons are the spine of the show, dozens of them featuring the little children who startled Americans so much starting in 1950, with a strip showing a character named Shermy watching Charlie Brown walking past.

"Good ol' Charlie Brown," Shermy keeps saying until Charlie is out of hearing. Then: "How I hate him."

This was the genius of Schulz: Week after week, he lanced adult beliefs about the innocence, happiness and blithe ignorance of children. He used children to satirize adults' fantasies about them, fantasies that have been making children's lives miserable since we emerged from the Middle Ages and acquired the odd notion that we could perfect the human race by applying abstract scientific theories to child-raising (not to mention everything else).

It is precisely this sort of fantasizing and theorizing that the rest of the show evokes.

Dr. Spock's lab coat and eyeglasses symbolize the sort of thinking that combined kowtowing to scientists with the new nurturance of suburbia, baby boomery and what McCall's magazine called "togetherness." You couldn't do it all by yourself. An ad for a 15-volume encyclopedia on child-raising warned: "Scientific research has proved that your mistakes in discipline can actually break your child's spirit forever!"

Captain Kangaroo's jacket and hat are here to symbolize our theories back then about authority figures, the need to learn the rules and obey them. Captain Kangaroo was gentle and nurturing, but so, probably, were Sheriff John, Captain Penny, Commander Riptide, Engineer Bill, Tom Corbett -- Space Cadet, and a ventriloquist known as Friendly Fireman, all of them heroes and exemplars of children's television. And all of them in uniform!

An educational film shows how to duck and cover if an H-bomb goes off while you're riding your bike -- "Attaboy, Tony, that flash means act fast!" says a baritone full of mesomorphic heartiness as Tony takes a header into the curb. Tony doesn't move till he gets the all-clear from a strange character in a raincoat and a helmet, the sort of creep that jails don't have enough of these days, you think, until he turns out to be a civil defense officer.

Also there are: a Davy Crockett cereal bowl, record and coonskin cap; Girl Scout blouse; Ding Dong School record player; Howdy Doody puppet; Hula-Hoop; Little Golden Books ("Make Way for the Thruway," "Animal Friends," "We Like to Do Things"); a little boy's bedroom with cap guns and Tinkertoys; horror comics, the very ones that were banned as corrupting our youth.

Pages from a Dick and Jane book show how Jane is supposed to look pretty, and Dick is supposed to play ball -- research, of course, had shown that the sexes had to be clearly differentiated to create happy children. Now research shows exactly the reverse, and we believe now, as we believed then, that we have arrived at a final truth, the last theory.

Most of this stuff bears the scuffs and long-ago dinginess of childhood (nothing looks older than your own youth), and a sense of the horrible anonymity of it all as we toiled away in our tininess under the aegis of adult expectation.

The theories were always changing, and still are.

In the past 10 years, for instance, we've gone from the free-to-be-you-and-me treatment, based on the notion of children as repressed innocents, back to locking these TV-addled savages up for more and more hours in schools, putting them in uniforms and herding them through the gamuts of standardized testing.

Some of it stays the same. We keep acting as if we are the first adults in history to say:

Things used to be simpler.

They grow up so fast now.

We listened when we were kids, but kids nowadays, they don't listen.

We don't let children act like children anymore.

The Smithsonian is no better than the rest of us in this regard. The show's epilogue gravely mulls the piety that "Parents now face challenges and fears unimaginable in their own childhood. How are they raising their own children? Today's boys and girls live in a menacing world over which their parents have little control -- and know it. They face imminent danger with new precedents and few clear answers."

Wait a second -- wouldn't those exact words have been true in 1945 as well? And 1968?

This is the truth that Schulz has always understood: that childhood is a squalid, frightening time of disappointed hopes, pointless patience, preposterous dreams, fading satisfactions, beautiful moments that can never be repeated, and so on. In short, childhood is pretty much the same as adulthood, except that as a kid you look forward to getting old enough to escape.

On adult fears of a strange new generation: Peppermint Patty tells her teacher that she's a latchkey child. "Yes, ma'am, we're a growing trend. No, ma'am, we have no plan to take over the world."

On adult memories of childhood: Snoopy the beagle tells Woodstock the bird, "I remember how green it used to be in the summer and then it changed to the most beautiful colors. ... You know that you were born and raised in a very special tree. ... Actually, I don't remember it at all. ... I can't tell one tree from another."

On Spockism: Lucy finds a book. "Well! What have we here? 'Your Child Age 3-5.' Well, well, well, well, well. I feel like a spy."

On child psychology: An earlier Patty says of another character who's upset, "Maybe he's frustrated or inhibited." Shermy goes to find out. He comes back and says, "His shoes are too tight."

On the carefree bliss of childhood:

Charlie Brown: "Did the little boy who sits in front of you at school cry again today?"

Lucy: "He cries every day! He has all the simple childhood fears."

She then offers an endless list of fears of school, of the principal, of not knowing what room to go to after recess, of bigger kids, of being asked to recite, on and on, until Charlie Brown cuts her off with his his customary sweet, bleak, existential "Good grief."

This is not to say that that childhood is always the same. Each era has its own spirit, or why did we bother to learn the word "zeitgeist" in college? Roger Kennedy, director of the museum, put it nicely when he said of the era described by the show: "It wasn't a nobler time than our own, but it was an easier time to feel noble."

That was part of the fantastic fraud back then.

Curator Charles McGovern has done a good job of cramming a small space with an uneasy combination of toys from the Smithsonian attic, "Peanuts" strips, symbols of the ethos of suburbia and souvenirs of the Cold War. The show almost -- but not quite -- finesses the fact that stuck in the middle of it is Irving Berlin's piano and Judy Garland's ruby slippers from "The Wizard of Oz" of 1939. It turns out these are permanent exhibits that would have cost too much to move, even with the financial support provided by United Media, the syndicator of "Peanuts."

The show runs through April.