Adolescence marks a critical period in the development of friendships. A variety of factors, such as growth in cognitive capabilities and strivings for increased autonomy from parents, contribute to the formation of close friendships in adolescence. Close friendships involve more affection and intimacy than friendships before adolescence. Although relationships to parents remain important sources of support, adolescents begin to seek more support and advice from friends than do children in early or middle childhood. Adolescents also spend more time with friends than do younger children.

Although adolescents may have some close friends with whom they spend much time and share many activities, they also begin to develop many friendships that are more specialized in nature. For instance, they may have friends with whom they engage in particular sports and other friends with whom they participate in the same school club or activity. Neighbourhood friends and school friends can also constitute relatively distinct groups of peers.

Adolescent friendship also tends to be distinguished from friendships in early and middle childhood by the establishment of friendships with other-sex peers. In early and middle childhood, the vast majority of friendships are formed between same-sex peers, and many children do not have any other-sex friends. In adolescence, most friendships are still with same-sex peers, but most adolescents have one or more other-sex friendships as well. Such friendships serve many of the same functions as same-sex friendships, but they may be differentiated from same-sex friendships in some respects. For instance, opposite-sex friendships provide opportunities for learning about the other sex and obtaining the perspective of the other sex. Such friendships may also contain some element of sexual tension. Also, other-sex friends tend to have less in common with each other and to engage in less self-disclosure, and other-sex friendships tend to be less stable than same-sex friendships.

Some individuals form friendships with other-sex individuals to whom they were initially romantically attracted. Conversely, some other-sex friendships evolve into romantic relationships. Even more commonly, these friendships can provide opportunities for heterosexual youths to find romantic partners, because an other-sex friend may introduce them to someone who becomes a boyfriend or girlfriend. Although far less is known about the links between friendship and the development of romantic relationships among homosexual adolescents, some research suggests that for both homosexual and heterosexual youths, other-sex and same-sex friendships may serve as a learning ground for developing the intimacy and connectedness that are part of most adult romantic relationships.

“Friends with benefits” is a type of adolescent friendship that seems to be relatively new and relatively specific to Western industrialized cultures. Such friendships involve some degree of physical or sexual intimacy but are not considered to be romantic by either party. Although research is under way on this topic, there is currently very limited knowledge about this specific type of friendship. One possibility is that friends-with-benefits relationships function to meet the physical and sexual desires that develop with puberty, and they may operate as a basis for some teenagers to learn about sexual experiences.

Adolescence is also marked by the emergence of romantic relationships. In many respects, these relationships can be considered a particular form of friendship. In fact, adolescents and adults often perceive their romantic partner to be their best friend. Just like other types of friendships, romantic relationships are characterized by affiliation and companionship. In late adolescence or in adulthood, these relationships may become more distinct from friendships, but even then companionship and affiliation remain important elements of these relationships.

Adulthood

Because adulthood encompasses a wide range of ages and life stages, the individual’s stage in the life course is an important factor in considering adult friendships. Life-course changes—such as the transition to marriage, the transition to parenthood, and the process of retirement—also affect friendship patterns.

Research on friendship in young adulthood has mostly focused on college students. Indeed, little is known about the friendships of individuals who marry or join the workforce directly after high school. Because of the nature of their environment, college students are likely to have a greater number of friendships than individuals who are not students. College students are surrounded by peers, and at least traditional full-time students have the time and opportunity to develop close friendships. Whether they are in school or in the workplace, young adults who are involved in a romantic relationship have fewer friends than individuals who are single.

This trend continues into middle adulthood. In particular, when individuals enter into marriage, both men and women seem to withdraw from friendships. Middle adults generally have fewer friends than college students. In comparison with friendships of younger adults, friendships in middle adulthood also tend to be more homogenous in terms of factors such as age, race, and social status. Adults also tend to have mostly same-sex friendships and thus have fewer other-sex friends than do adolescents. This trend may in part occur because social norms portray other-sex relationships as a threat to marital relationships. The decrease in frequency of friendships and the increase in homogeneity of friends during this period may also reflect the environments of most adults in middle adulthood, with fewer peers and potential friends. In addition, adults’ lives are typically more multifaceted and more complex, often occupied by family, parenting, and careers.

Friendships among older adults take place in different contexts from friendships in middle and young adulthood. This age and life stage is often characterized by events such as retirement, relocation, widowhood, and deteriorating health. These transitions produce some increases and some decreases in older adults’ ability to form and maintain friendships. For instance, retirement eliminates work as a source of interaction with possible friends. Widowhood, on the other hand, may encourage individuals to look to friends more often for support and companionship.