What is Adulthood?

At its basic biological level, adulthood is defined by physical growth and sexual and reproductive maturity. But there are both social and legal definitions of adulthood that are more important to us than simple biological maturity. Traditionally, in many cultures throughout the world, the standard makers of adulthood are establishing a career, marriage, home ownership, and having children. However, as our society has been moving away away from strict social and religious traditions and towards the expansion of civil rights and the rise in individualism, the designators of adulthood have been shifting from external markers to internal ones.

With his 1950 book, Childhood and Society, Erik Erikson pioneered the field of Psychosocial development, which explains how personality and identity develop throughout a person’s lifespan. He believed that people continue to grow and develop psychologically through their entire lives. His Stages of Psychological Development theory posits that humans go through 8 sequential stages of social and psychological development, 3 of which occur in adulthood: Young Adulthood (ages 18-40), Middle Adulthood (ages 40-65), and Late Adulthood (ages 65 and up). Prior to Erikson's theory, it was generally accepted that adulthood was a stagnant period during which developmental changes ceased to occur.

Despite his groundbreaking theory, Erik Erikson still maintained that true adulthood begins at 18. In the early 2000s, psychologist Jeffrey Jensen Arnett identified a new life stage between adolescence and adulthood, called Emerging adulthood. Arnett asserted that including this stage is necessary because of a change in social norms and expectation that has led to the modern trend of young adults delaying the pursuit of traditional adulthood markers such as marriage and parenthood. Emerging adulthood acts as a bridge between the dependence of childhood and independent adulthood. During this stage, young people explore their identity, acquire skills, and become more and more self-sufficient.

A 2024 study by the University of York revealed that many people are experiencing the Emerging adulthood stage of development identified by Arnett. By surveying over 700 adults, researchers discovered that there has been a dramatic change in people’s definition of what adulthood entails from that of earlier generations. Approximately 80% of this study’s participants defined adulthood by psychological attributes such as accepting responsibility for one’s actions, making autonomous decisions and financial independence. Traditional markers of adulthood have not disappeared, but they are far less valued.

One of the most profound changes in our modern culture has been the development of our understanding of human psychology and identity and this has led to changes in our definition of adulthood. It is now understood that establishing one’s identity for one’s self is a necessary aspect of true psychological adulthood. Starting in adolescence but lasting one’s entire lifespan, a person’s autonomy and self-defined identity is closely connected to mental health and self-actualization. We now know that there many successful life paths and that it is the individual’s prerogative and privilege to determine what that means to them.