During early childhood, the main ingredients in forming friendships are opportunity and similarity. To become friends, children need to be available to each other for play and other activities. Children become good friends when they spend a lot of time playing together, sharing toys, and enjoying the same games and activities. Children who are neighbors, relatives, or schoolmates spend more time with each other and therefore have more opportunities to form friendships. Children's social contacts increase dramatically when they enter school. In school, children encounter a much larger group of peers and tend to have less direct adult supervision when they are together. From the toddler period to the school-aged years, time spent with peers triples (Higgins & Parsons, 1983). Also, like adults, children are drawn to others who are like them. Friendships are more likely to form when children are similar in characteristics such as age, gender, race, attitudes, beliefs, or even play styles (Epstein, 1989; Hartup, 1989; Rubin, Lynch, Coplan, Rose-Krasnor, & Booth, 1994). Social networking is also an important feature of friendships. When parents get together frequently with other parents, their children can become friends. Sometimes the reverse happens: Children are friends first, then the parents meet each other and develop parent friendships. Either way, children benefit as parents communicate with each other, help each other monitor the children, and work together to support their children's friendships (Fletcher, Hunter, & Eanes, 2006).

Best friends is a special category of friends. A child's relationship with a best friend is closer and more exclusive than are relationships with the more casual acquaintances most children refer to as "friends." When you ask children to name their "best friends," the number that they report tends to increase until about age 11, and then children become much more selective in whom they designate as their best friends (Epstein, 1986; Rubin et al., 1998). In one study that is often cited, Bigelow (1977) asked Canadian and Scottish schoolchildren what they expected in their best friends. First graders most frequently reported that having common activities was important. By the eighth grade the most important trait was an admirable character, followed by common activities, acceptance, loyalty, and commitment. Only girls mentioned the potential for intimacy (sharing personal thoughts and feelings) as an important feature, and only after the fifth grade. Children rarely mentioned physical attractiveness as an important characteristic in best friends. Also rarely mentioned were shared personal characteristics (such as both friends being shy).

Based on research findings, we can say that children's close friendships typically progress through the following three phases (Berndt, 1986; Bigelow, 1977; Rubin et aI., 2006; Smollar & Youniss, 1982):

  • Play-based friends (ages 3 to 7 years): Play-based friendships are the most common for younger children. Children are good friends when they spend a lot of time playing together, sharing toys, and enjoying the same games and activities.
  • Loyal and faithful friends (ages 8 to 11 years): Loyalty, faithfulness, and generosity define close friendships during middle childhood. "He shares his best things with me," "She sticks by me when other kids tease me;' and "She doesn't ignore me when her other friends are around" are common descriptions of close friends during this second phase.
  • Intimate friends (adolescence and beyond): Intimate friends share their most personal thoughts and feelings. They trust each other to keep personal secrets, and they use each other as a safe base for exploring issues and problems that they may not discuss with anyone else—including parents, teachers, or close siblings. During adolescence, intimacy and self-disclosure distinguish best friends from other friends. Intimacy emerges in early adolescence for girls but only in later adolescence for most boys (Berndt, 1986).