How grown-ups actually make and keep friends

Think back to a friend you made in school.

You probably did not plan it. It just happened. As a grown-up, that almost never happens by itself. There is a real reason. And it is not you. Researchers have studied this since the 1950s. One sociologist, Rebecca Adams, named what close friendships need.

She points to three things that grow friends. First, being near the same people. Second, running into them again and again, by accident. Third, a place where people relax and open up.