Image zoom Credit: Getty Images. Socialization begins in early infancy when babies cry, smile, and coo at their caregivers. Friendship naturally evolves from these early expressions. It evolves so naturally that adults don't always take time to explain the concept to children until they have their first fight or friend breakup. "Giving [friendship] a label early on [gives] kids...a greater...understanding of themselves and their peers," says Molly O'Shea, M.D., a pediatrician for Goldfish Swim School in Bloomfield Township, Michigan. Adults can start talking about friendship with children as early as 9 months, and realistically, children will begin to better understand what a friend is as they start having more peer-to-peer interaction around 2 or 3 years old.