(FORTUNE Small Business) – John Molloy may have coined the phrase with his how-to books in the late 20th century.

But dressing for success has been a dilemma for powerful women since Cleopatra had to figure out how much kohl to put on. For 100 years--at least until the rise of casual Fridays--men had it simple. Their biggest wardrobe decision was which color tie to wear. Women have more questions to answer, and some of those questions are heavy with symbolism: Wear the pants? Let down your hair? Wield that cleavage or conceal it? Other questions are practical: How did Mary Pickford stand around the set all day in heels?

If there are few women here who ran a business, and more who went on stage, sold lipstick, or fought the good fight, that's only natural. It has long been easier for women to gain clout on the fringes, or where the stakes--at least in dollars--were lower. As women have wrested power, they have often bowed to men's sartorial example: exhibit A, the floppy bow ties of the 1980s. But borrowing from the guys has been mostly about comfort. Since Chanel, women have helped other women get out of clothes that cramp their style (corsets, pantyhose) and into clothes that let them get the job done. New looks have also inspired new attitudes. Juliette Low's own scouting uniform looked decidedly martial, especially in a day when women went to the front only as nurses. But getting millions of girls to build campfires surely helped speed the day when they could also fight for their country.

--JOLIE SOLOMON AND MARY SEARS

1900

1905 Madam C. J. Walker Selling her hair-care formulas door to door, she built the biggest black-owned business of her day. Style: Black power

1909 Coco Chanel Took women out of corsets and into chic comfort: cardigans, trousers, little black dresses, and pearls. Style: Suit yourself.

1910

1912 Juliette Low Her Girl Guides became U.S. Girl Scouts, teaching millions of girls how to light fires and push Thin Mints. Style: One tough cookie

1914 Mary Pickford "America's sweetheart" also reigned as Hollywood's first female mogul, controlling her own movies and co-founding United Artists. Style: Walk softly and carry a big megaphone.

1914 Helena Rubinstein Polish emigre started her empire selling cream at $1 a jar, conquering the beauty world with her vivid presence. Style: Flaunt it.

1920

1929 Martha Graham No dainty ballerina, she changed dance forever, and put her own name on her troupe. Style: Bold is beautiful.

1930

1933 Eleanor Roosevelt Statuesque First Lady chose hats that added an inch; wielded public influence long before Hillary. Style: No apologies

1940

1945 Mildred Pierce Joan Crawford showed us how to conceal a handgun in a full-length fur coat. Style: Cool as steel

1950

1951 Lucille Ball Raucous redhead was the first woman to show up pregnant on TV. Bought Desi out of Desilu, became the first female to run her own production company. Style: Glitzy, not ditzy

1952 Margaret Sanger One of 11 kids. Went to jail for teaching that biology ain't destiny; founded Planned Parenthood. Style: Can't keep me barefoot and pregnant

1960

1960 Jane Goodall Leading primatologist never let the African climate put a chimp in her wardrobe. Safari gear isn't just for tourists. Style: I'm evolved, how about you?

1963 Mary Kay Ash That big bouffant hides big brains. Her direct-sales cosmetics firm--larger than Avon--hands out trophy Cadillacs to top salespersons. Style: Pink power

1965 Helen Gurley Brown Told Cosmo girls: Sexual revolution isn't just for guys. Told Seven Sisters' publishers: Mags aren't just for moms. Style: Working girls just wanna have fun.

1967 Muriel Siebert First woman with a seat on the Big Board. Style: You can trust me with your dough.

1969 Katharine Graham Socialite inherits Washington Post; stars at Capote's masked ball; stares down White House in Watergate. Style: Fearless

1970

1971 Gloria Steinem With her streaked mane and miniskirts, the co-founder of Ms. magazine demonstrated that even fervent feminists can be fashionable. Style: Free to be you and me

1980

1984 Donna Karan With her neutral palette and forgiving knits, this designing woman freed her sisters from confining, traditional suits. Style: Comfort equals power.

1986 Oprah Winfrey Richest self-made woman dishes on weight problems and spirituality. Style: Everywoman--give or take a hundred mil

1987 Baby Boom Power babe Diane Keaton chucks it all for adorable baby, moves to Vermont, then gets it all back with baby-food biz. Style: Inside every ball-buster is a mommy.

1988 Murphy Brown Take-no-prisoners single mom laughs at enemies, makes us laugh too. Style: Casual elegance, calculated career

1990

1990 Ani DiFranco Punk-folkie defies music industry to run own label, keep Buffalo, N.Y., homies in jobs with her Righteous Babe Records. Style: The nose ring as CEO accessory

1996 Martha Stewart Stockbroker turned insomniac Omnimedia queen casts wide net across all things domestic. Style: I can rule the world and still decorate Easter eggs.

1999 Carly Fiorina CEO of Hewlett-Packard, became cover girl for our sister mag FORTUNE. Style: Confidence counts.

2000 and Beyond

2000 Hillary Clinton From headbanded do-gooder to tousled "glamorista" to senate croptop. Wore out six black pantsuits in campaign; switched to blue for victory. Style: Watch this space.