When you were a kid, it seemed like you could walk up to just about anybody and be best friends the next minute. But somewhere along the long, winding road to adulthood, making new friends became an impossibly hard thing to do. Well according to psychologist and University of Maryland professor Marisa G. Franco, that’s because as you get older, making friends no longer happens organically. “Sociologists have kind of identified the ingredients that need to be in place for us to make friends organically, and they are continuous unplanned interaction and shared vulnerability,” says Franco, who is writing a book on making friends as an adult. “But as we become adults, we have less and less environments where those ingredients are at play.”