Our friendship began more than 19 years ago when we were next-door neighbors. Her youngest daughter was born the day before my oldest son, and the two of them grew up together, rolling side by side down the gentle slope that separated our houses and thinking it was a great, steep hill, indeed. When my friend's family moved to London for three years, her youngest daughter took with her a photo of my son and the memory of that slope, and when she returned home she was shocked to discover that it was not the great hill she remembered, but a slight incline. She was 7 then and growing up.

In the years that have passed, certain things separated the two families and many things brought them together: We moved to a larger house, less than 10 minutes away. But when they went back to London for a year's assignment, we visited them, and when they returned to the United States, we began going to the beach together in the summers.

Traditions evolved: My birthday, for example, is on Christmas Eve and it became a shared event, with my family stopping by their home before or after dinner at my parents' home. One year, their family -- the parents and four children -- showed up at our front door, caroling. Another year, they surprised us at my parents'. Last year my birthday dinner was at their home, and it was a wonderful, rowdy gathering with seven children who have grown up together and who share an extraordinary closeness. At Christmas we exchange presents: books, flowers, candy and last year, wind chimes for their new beach house, which they built on the Outer Banks of North Carolina, fulfilling a dream that was born and nurtured during the many summer weeks that we spent together at the beach.

Over the Memorial Day holiday, my friend and I drove down to their new house with my two younger children. Her husband had to work. Our families have changed: Two of her four children are now working, the other two are still in college, as is my oldest. But the memories of times at the beach have not changed. When my son the 9-year-old found out for sure that we were going, the first thing he asked was whether we could go for night walks on the beach, one of my friend's great pleasures. He and his sister the 5-year-old also wanted to know whether we could play "moon tag," not realizing that two grown women might have less enthusiasm for this adventure than a group of madcap teen-agers.

We drove down through a torrential rainstorm, but the skies cleared late in the day as we crossed the span toward the Outer Banks and drove to the remote spot near the ocean where our friends have built their home. It was cold, and we bundled up before going for the traditional evening walk on the beach. It was not long before the children were scampering into the icy waves, and it wasn't long before they were both soaking wet and shouting with laughter. We found shells and dead sea creatures, which we examined, as my friend, a former schoolteacher, pointed out the eyes, teeth and webbed feet.

The next day was nicer and we spent it on the beach. For the first time in years, I did not have a child who had to be watched closely and constantly, a small but nice landmark in the growing up of one's family. At night we watched the sunset, gathering on the deck to witness one of the most beautiful sights on earth. Another tradition. And then we cooked together in her kitchen, enjoying once again the fact that for whatever reasons, we work well together.

We took long walks and had long talks, exchanging confidences about our current lives, seeking advice and giving it freely. I was struck by the number of sentences that started with "remember the time that . . . . " And they were memories about the children, about other beach houses we had shared, including the time they had driven through a downpour to a house in Virginia Beach that I had rented and found themselves in front of a shack. I do not think I will ever forget the look of relief on their children's faces when they finally arrived at the right address.

We live in a society that is constantly on the move as we follow careers to new cities and towns, distancing ourselves from family members and often not staying in one place long enough to form great, long-lasting friendships. In that sense, by fortune and design, our families have been lucky. We have celebrated the ceremonies and joys of life, and been there for each other through its sorrows.

You don't hear much about family friendships that span nearly two decades these days, but when it occurs it is a treasured gift.