"Know the truth. . .and it will make you either scared, mad or sad," Clare Boothe Luce says.

The former congresswoman, ambassador, journalist, playwright and society hostess delivered a commentary on women's progress toward equality that was bleak but not without humor and encouragement for 350 female entrepreneurs gathered here last week.

The truth according to Luce: All the "significant professions" remain overwhelmingly "the bosslands of the power-hungry, money-grubbing male."

Luce, peppering her remarks to the Washington chapter of the National Association of Women Business Owners with witticisms and personal reminiscence, emphasized her status as "an old-fashioned feminist" who believes in equal pay for equal work.

She spoke of working as a teen-age lobbyist for ERA author Alice Paul, of drinking champagne with her suffragette mother the day women won voting rights in 1920, and of how little effect women's right to vote has had on the male dominance of "our public institutions."

Women share half the blame for their overall lack of progress, she said, pointing to the dying Equal Rights Amendment as evidence. Introduced into Congress 59 years ago, the ERA has been prevented from passing by "the failure of a majority of the majority of the voters--who are women--to support it," she said.

Despite what she described as an underlying culture of male dominance, the feisty 79-year-old managed a note of optimism.

The real road to equality, she said, is the willingness to assume responsibility and to assert authority. Drawing on Virginia Woolf's "A Room of One's Own," Luce concluded that "a business of her own is a fine path to emancipation from both the true fact of the inequality she suffers in a male-owned business today and the false notion of female inferiority."

Other maddening, saddening truths, according to Luce:

* Men make all the crucial political decisions and collect all but a fraction of the top jobs and top fortunes, which they keep until death. "Widowhood all too often is the only fringe benefit of marriage," she noted with a straight face.

* In the 62 years since women received the ballot, only 14 of about 1,750 U.S. senators have been women and only seven of those were actually elected.

"The others were appointed to fill the unexpired terms of their expired husbands," she said.

When Luce was a member of Congress from Connecticut 40 years ago, there were 10 women representatives, she said. Today there are 19. Only five women have been elected governors; less than 9 percent of state and local elected officials are women. Fewer than 40 women have held the rank of ambassador, only six in what Luce termed "major countries." (She served in Italy as Eisenhower's envoy.)

Looking for a "self-made business millionairess," Luce said only heiresses, actresses, entertainers and novelists were evident examples. Similarly, she recounted the negative portrayals of women on television and in film--"dumb and submissive . . . kooky working girls . . . smart girl-Fridays . . . sex objects."

The mere presence of large numbers of women in the labor force does not represent progress toward equality, she maintained. Quoting a 1979 Labor Department statistic, she noted the average female worker makes less than 56 percent of the average male's pay. The gap has been steadily widening, according to the Labor Department's Women's Bureau.

Luce, seeing the country trending toward a welfare state, said, "The vast majority of persons on relief are women and their children.

"And that's progress?"