THEIR NAMES ARE Charles and Margaretta Warden and last Friday night they celebrated their 50th wedding anniversary at their home in Arlington. Gathered around them were 50 friends from as long ago as 1943 when they moved here from New York after he joined the War Production Board. There were friends they made in Paris when he was with the Marshall Plan, and friends they made in Washington when he returned to work here in the foreign aid program, and friends they have made in their retirement. Gathered around them, also, were their seven grandchildren and three children, of whom I am one.

It was a loud, happy party, with many people being reunited across the years, many memories exchanged, and lots of champagne and singing. And for some of us there was the feeling that we were watching a generation celebrate an accomplishment that our generation will likely not repeat. Theirs was perhaps the last generation in which divorce was unthinkable, in which marriage was for life, in which the wedding vows were the foundations of permanent families, of stable social structures to which children and grandchildren could return over the years for friendship, comfort and help.

It was a social structure that worked for their parents and worked for them. It was a way of life they tried to pass on to their children, one which we have challenged in recent years, but not successfully replaced.

There were tableaus of my parents' marriage that came to mind during the party, quick private pictures of what I saw inside the family, things I saw between them that made their marriage work.

They did not always have an easy time of it: They were married in 1929 when my father was a stockbroker, and my mother was running the Arthur Murray studio in New York City. The Depression brought role reversals long before that was chic. Yet, they always took pride in the other's accomplishments. Neither partner was subservient to the other, there was no little woman, no question but that they had entered into a full and equal partnership. Both have strong personalities, but their disagreements never got personal, malicious, or mean. The angriest thing we have ever heard one say to the other was: "Goddamnit, honey . . . "

They share mutual goals in life and mutual standards. They value hard work, thrift and restraint.But they also have appreciated and value art, travel, good food, good wines. They enjoy good music and collect it, and good conversation and good friends. They have enjoyed each other more than anyone else.

They have always been busy, always making plans, always looking to the future. They created an atmosphere of activity within the family. Even during the ritual cocktail hour before dinner, when the day's work is done and it is time to relax, and talk, my mother has always been doing something with her hands: sewing, assembling work for a course she was teaching, going over homework for a course she was taking, playing checkers or pickup sticks with a grandchild.

When the children were growing up, the cocktail hour was a time for gathering in the living room and hearing our parents talk and a time to get them to help us with homework. My father helped us with math and science, my mother with French, English, Spanish and Latin, and they would take turns helping us learn to write. They prized clear, forceful composition.

And they prized education and books. They sent all of us off to good, expensive colleges, and there was never any question that my sister and I would have the same access to education as did our older brother.

My father always shared with my mother and his children his feelings about his work, details of what had gone on during his day. He would often write speeches at home and try them out on us or our mother, and he listened to our opinions. We were not put down, devalued as people, simply because we were children.

There were, of course, nights when he would come home from the office in a mood, nights when mother would firmly suggest that we do our homework in our rooms, that father had had a bad day. Invariably, she would wheedle out of him during the evening the details of what had gone wrong and share the information with us later - not to satisfy our curiosity, but to keep us aware and involved. We always knew that we were part of a family, that we, too, should know the bad things that happened to each other, as well as the good.

Mostly it was good. Most dinners were the scene of lively discussions, ranging from foreign affairs to economics to art to current literature, newspaper articles, politics. Some nights there were language games in which we challenged each other to conjugate verbs in whatever foreign language someone was studying at the time. Other nights we did history or geography or current events. We made side belts on who was right and trotted out schoolbooks and dictionaries and encyclopedias to prove points.

They were happy, loud, stimulating dinners. Later, as we got older and our parents became more conservative, there arose political splits in the family and occasional dinner table debates that turned bitter. We went from language games over the civil rights movement, the war in Vietnam, Nixon and Watergate.

No one ever said it in so many words, but one by one we children and our spouses decided that they were certain topics that were better not discussed in our parents' home. The political divisions of opinion were deep and, in the long run, in terms of family harmony and affection and respect we shared for each other, those political divisions were not worth fighting over.

Our parents tired to teach us the qualities they admired in other people. They taught the merits of truthfulness and tact, of manners, of being constructive in our criticism, or working with other people, or respecting other people's knowledge and opinions. They taught us that it was right to care deeply for others, to be loyal.

They taught us the value of self-discipline, and of setting goals for ourselves and our children, rather than accepting limitations. Mother, particularly, taught by her example. She was never the traditional stay-at-home housewife. Even when my parents were stationed abroad, she plunged into a variety of charitable projects and language studies and made sure that the family got to every corner of Europe we could visit during the years we were there. For years she has earned money painting, and when she was 60 she went back to school to learn how to teach foreign languages. She still is teaching part-time today.

They taught us the enduring worth of marriage and of families, nurturing a sibling closeness and respect that exists among their children and grandchildren now. They established a model for us of what a marriage can be: a permanent, dependable union, forged and strengthened over the years through compromises, occasional angry words, and a deep, trusting affection for each other. They set high standards of right and wrong, high standards for themselves and those around them. But when we fell short or failed, they were always there to help us out.

There came a time for toasts last Friday night, and my brother lifted his glass of champagne to our parents and their guests. He said that a measure of what kind of people our parents are is the kind of friends they have had. "I would like to offer a toast to them, and to all of you who are such wonderful friends of theirs," he said.

Then my father lifted his glass and spoke:

"Welcome to our house. It's been a long, long wonderful marriage. I don't know any reason - I may not be able to finish this - that a couple could be so happy as we have been.

"I want to do two or three things. One, to thank our parents for giving us the strength, the will and the tradition to go through a long life such as we have. We want to thank our God for protecting us. I want to express our appreciation for the wonderful country we live in. We have been a part of it, and I hope we've added a little bit."