What was going on when I was born?

Mary Decker, the world's most successful female distance runner, made the United States Olympic team tonight. So did August Wolf, a 1983 Princeton graduate who until three months ago was a journeyman shot-putter. Their heroics excited the crowd of 20,247 watching the United States Olympic track and field trials at the Los Angeles Memorial Coliseum, the site of the Olympic competition six weeks from now. But nothing caused more stir than the blanket finish in the women's 100-meter hurdles.

Soon to rise on a 24-acre site embracing a large piece of blighted urban renewal land in Glen Cove, L.I., will be a 328-unit residential condominium complex called Captain's Cove, overlooking Hempstead Harbor. The condominium project, off Dickson Lane, is part of a $100 million development program for the city by the GEO Group of Glen Cove and its subsidiaries.

-room Mediterranean style villa filled with priceless antiques might sound dramatic, but Michael Sweeley has become used to the experience. ''In a sense, I'm living over the store,'' he said, smiling, standing in a room whose vaulted ceiling was once part of a 16th-century Italian castle. ''A very grand store, but still, living over the store.'' Mr. Sweeley is executive director of Caramoor, the museum in Katonah that once was a private mansion and is each summer the site of the Caramoor Music Festival. Saturday, the festival opens its 39th season, and Mr. Sweeley begins his 30th year coordinating the event.

LOS ANGELES LAURIE FLACHMEIER spent her first week off since last Thanksgiving relaxing. Well, even sailors get to go on leave now and then, so why shouldn't the United States women's volleyball team be entitled to a few days of R & R? But while Miss Flachmeier was lying in the sun recently, resting her weary bones, her mind continued full speed ahead, cluttered with Olympic thoughts swirling around in an emotionally draining whirlpool. It occurred to her, she said, that it probably would be foolish to pretend she was just a college girl on a summer break. Living as she does near the volleyball team's permanent training center at Coto de Caza, Calif., there really isn't any way that she could avoid thinking about the Los Angeles Olympic Games or seeing physical evidence that they are close at hand. ''There are so many commercials on TV that it's not going to slip your mind,'' Miss Flachmeier said. ''There was a Saturday when I was driving in my car, watching people go past and I looked at them and thought, 'This is an ordinary day for an ordinary citizen. But in six weeks, I'll be in the Olympics.' I wondered whether there could be anything in their lives that could be like this.''

IN the last five years, condominium and cooperative apartments in prewar town houses, once viewed as the choice of just a few idiosyncratic developers and buyers, have become a significant part of New York City's private housing market. Brokers, developers, and housing experts say the number of owner-occupied apartments in town houses is substantial and growing, although there are no statistics to measure their popularity and acceptance. They can be found in all of the city's town- house and row-house neighborhoods, in Chelsea and Greenwich Village as well as the Upper East and West Sides in Manhattan and in Fort Greene, Clinton Hill and Boerum Hill as well as Park Slope and Brooklyn Heights in Brooklyn. ''The town-house condominium and cooperative market is very strong,'' said Neil Binder, a broker with Bellmarc Realty. ''People want to buy, and many buyers who won't accept an apartment in an elevator building without a doorman will accept one in a town house.''

WASHINGTON O N the road again and on a roll, President Reagan came out last week in favor of sportsmanship, sobriety and safe streets. With each passing week, his approval ratings seem to continue their climb. Senior advisers acknowledge their failure to rid Mr. Reagan's re-election organization of overconfidence. On Capitol Hill, however, the President was finding the road somewhat more bumpy. Most of his military spending program for fiscal 1985 was approved by the Senate, but only after Republican allies felt it necessary to challenge him on arms control. To win Democratic support for his proposed budget cuts, Mr. Reagan had to accept a loss of some election-year goodies, such as extending Individual Retirement Account tax breaks to nonworking spouses. For all the political and legislative combat in Washington, Mr. Reagan was sticking to his generalized themes that appeared tailored to make him sound, to the larger audience beyond the capital, as little as possible like a candidate for re-election. At a conference of sheriffs in Hartford last week, for example, Mr. Reagan denounced ''liberals'' for blocking his anticrime package. Had he directly criticized Democrats, his re-election campaign might have had to pay for the trip.

In the dense and bustling commercial neighborhood where 43d Street meets Lexington Avenue - dominated by such landmark structures as the Chrysler and Graybar Buildings - Olympia & York, the Toronto-based development company, will erect a 30-story office building.

TOMORROW, when the space shuttle Discovery makes its scheduled liftoff from Cape Canaveral, Charles Walker will be on board, a pioneer among astronauts. The McDonnell Douglas engineer will be the first person from private industry to voyage into space, and with him a new era for business will be launched, one that could extend forever the frontiers of corporate America. ''It's a new area, an area that is providing a great service to mankind in general, and it's one of the most exciting technologies for our future corporate activity,'' said an exuberant John Yardley, president of McDonnell Douglas, of the experiment that his engineer will conduct on board. In fact, he said, ''we're a little nervous we won't be able to expand fast enough, once demand for the products builds.'' The journey to space by Mr. Walker, a 35-year-old ''commercial payload specialist,'' could lead to the development of the first product made in space by a private company, a new drug that scientists and analysts say could be a major advance in the treatment of diabetes. In tests during four previous shuttle flights, the hormone that Mr. Walker will work with proved to be up to 700 times larger and four times purer than any produced on earth.

THE MIRROR MAKERS A History of American Advertising and Its Creators. By Stephen Fox. Illustrated. 383 pp. New York: William Morrow & Co. $17.95. ADVERTISING has always been the Peck's Bad Boy of American business. Unlike most goods and other services, which tend to be taken seriously, its products are words and pictures, urging us to buy things we probably don't need and often can't afford. (Nor is advertising necessarily a ''service.'' After all, we don't request its presence, as we do a plumber's.) Even so, it is impossible to visualize an America without it. And many of us secretly enjoy the sassier commercials and elegant layouts, not to mention being told of impending sales. Stephen Fox has written a fascinating account of what may well be this country's most characteristic institution. ''The Mirror Makers'' moves from the earliest print shops to international agencies, with sources ranging from scholarly archives to personal interviews. The book is fun to read, but then the subject is a natural; advertising is an industry where egos loom large and methods verge on the outrageous. At the same time, the author is a trained historian, concerned with the power of advertising as a social force. His thesis, about which more momentarily, makes a great deal of sense.

HOUSTON T AKEN in the long historical sweep of things, there is perhaps no more contradictory theme in American life than immigration. Above all, the United States has defined itself as a land of newcomers, a refuge for the downtrodden and persecuted. It has welcomed wave upon wave of bedraggled migrants, if only, sometimes, because their labor was needed. Indeed, in the case of one large immigrant group - African blacks - the trip was nearly always involuntary. But periodically, the Anglo-Saxon majority has rebelled against these influxes, fearful that the American character, however defined, was being somehow permanently altered or diluted by the strange newcomers.

Here are the major components of the $50 billion tax bill approved today by conferees from the House and the Senate. The bill needs approval by the full House and Senate before going to the President. Revenue figures were not available for many provisions; those given are preliminary estimates for the increase or decrease from 1984 through 1987. Capital Gains The capital gains holding period to qualify for preferential tax treatment is temporarily reduced from one year to six months. Previously an investor had to hold securities or investment property for more than a year before selling in order to obtain the preferential tax rate of 20 percent. Effective on assets purchased after today. Revenue loss $640 million. Consumer Taxes A $2-a-gallon rise in the liquor tax, from the current $10.50 to $12.50, effective Oct. 1, 1985. It will raise the tax on a fifth of 86 proof liquor by 34 cents.

Since 1970, I have added 73 new biographies of women to my library. That does not include autobiographies, volumes of letters, diaries and journals or biographical essays. I am a collector of biography and a student of the form, but these numbers are out of all proportion to what might have been predicted by a competent statistician surveying my library 15 years ago. Before 1970, biographies of women were scarce and rigidly restricted in subject matter - only royal women or those who were attached to powerful men easily qualified.