THE GOOD OLD DAYS were hell on earth for an awful lot of Americans. Beneath the glitter of the Gilded Age and the glamour of the Roaring Twenties lay such social ills as illiteracy, cruel exploitation of children and immigrants, widespread disease, deadly drinking water and contaminated food.

So what's new, cynics might say. Yet the fact that we're so quick to rise in wrath when current problems are revealed is a measure of how high our standards and expectations have risen.

Who made us so socially aware and demanding?

Mom.

While not claiming that it's quite that simple, an absorbing new exhibit at the National Museum of American History gives women the lionness's share of the credit for the great reform movements that swept the United States at the turn of the century.

The Smithsonian dates the reform era from 1890, when "the weaker sex" still was legally defined as inferior and subordinate to men, to 1925, by which time the Suffrage Amendment had given women direct access to political power and the concept of public health, education and welfare had become institutionalized. The movements involved millions of women, and marked the beginning of the end of the man's world.

At first the movement worked mainly through moral force, which generally meant shaming men into doing the right thing, or at least into being a little less brutal. ("They don't feel pain, they don't even speak English," a mine owner said when taken to task for the rate at which small boys were being maimed while picking slate from his coal.) Many of the 17 million people who immigrated to America from 1890 to 1924 went straight from Ellis Island to the sweatshops.

But clubwomen nagging their husbands could accomplish only so much. What seems to have really made the ball roll was an alliance between rich ladies of conscience and tough women of the tenements. The classic example of this class-defying sisterhood was Chicago's Hull House, Jane Addams's Nobel Prize-winning social experiment, founded in 1889. Here women were expected and required to be innovative, forceful and effective in working for peace, good government and social progress.

This was heady stuff for upper-class ladies who'd been trained from birth to be demure, decorous and decorative, and for lower-class women who had been repressed, starved or beaten into submission. And it was equally mind-bending for their men, according to British socialist Beatrice Webb:

"The residents consist, in the main, of strong-minded energetic women, bustling about their various enterprises and professions, interspersed with earnest-faced, self-subordinating and mild-mannered men who slide from room to room apologetically . . . ."

The national reform movements embraced everything from the kindergarten advocates, who advanced the revolutionary idea that all children are entitled to childhoods, to the fight against white slavery. This was a time when boys of five or six took bets and peddled newspapers on the streets from dawn to dark, and when the sweatshop or the brothel were real choices for many a young girl.

The techniques used by the movements ranged from direct action -- thousands of women went to jail for participating in such criminal activities as wage strikes and carrying suffrage posters -- to "womanly" indirection: When the robber barons blocked legislation forbidding the employment of young children in mines, mills and factories, women lobbied for compulsory school attendance laws. Who could be against education?

Winning the vote was of course the key to real political power. The exhibit does not fail to mention the antisuffrage campaign mounted by traditionalist women, nor the race-baiting tactics of some white women, who promised that their votes would preserve the white voting majority threatened by growing numbers of black male voters. Many of the do-gooders arrogantly imposed their own "superior" culture on those they chose to help. The Smithsonian is commendably committed to warts-and-all explication of American social and political history.

The most moving parts of the exhibit are about the women who rolled up their sleeves and did it themselves. Mary Breckenridge, a well-born Southerner, rode horseback through the roadless Kentucky hills, treating the sick and teaching child care, sanitation and nutrition. The women of her Frontier Nursing Service reduced the rate of deaths in childbirth in that Appalachian outback to well below the national average.

In 1909 Washington's Nannie Helen Burroughs (1878-1961) founded the National Training School for Women to teach reading, writing and job skills to her impoverished black sisters who came to the nation's capital from the rural South seeking work. "We Specialize in the Wholly Impossible" was the school motto.

Unmeasurable but vital was the ambition that such women stirred in others, including my mother, who was born in a remote North Carolina mountain cabin in 1897. Although at that time no man from Swain County -- not even the superintendant of schools -- had ever gone to college, Blanche Tabor from girlhood was determined to become a doctor. She finished working her way through college and medical school in 1929.

While the exhibit has all the clutter and curious lapses that have become the standard at American History, it's an obvious hit with visitors. Children especially are arrested by scenes of pinch-faced, raggedy kids their own ages laboring in mills and mines; fathers seem to find it particularly difficult to explain how come women didn't used to be able to vote.

The lapses range from photos and other items unidentified by date or place, to obvious lacunae. We're not told how Hull House got its name or what became of it or of Burroughs's school. And how is it possible to mount an exhibit on the women's reform movement without mentioning such great muckrakers as Ida Tarbell (1857-1944), who got the goods on Standard Oil?