As generations continue to adapt, new markers of adulthood are created that add different social expectations of what it means to be an adult.Daniel Levinson suggested that the first phase of early adulthood comes to a close around twenty-eight to thirty, when 'at about 28 the provisional character of the twenties is ending and life is becoming more serious...we must make crucially important choices regarding marriage, family, work, and lifestyle before we have the maturity or life experience to choose wisely.' While 'young adulthood is filled with avid quests for intimate relationships and other major commitments involving career and life goals', there is also "a parallel pursuit for the formulation of a set of moral values".Reaching adulthood in modern society is not always a linear or clean transition.A young adult is generally a person in the age range of 20 to 39 (or 40), although definitions and opinions, such as Erik Erikson's stages of human development, vary.
The study also shows that many American adults young adults report more positive feelings about their families when they do not live in the same household.Because the rapid and numerous changes often characterizing this period may be overwhelming, young people may find the services of a therapist or other qualified mental health professional to be beneficial as they transition from adolescence to adulthood.The young adult period is characterized by rapid physiological, sexual, cognitive, and emotional changes.A person in the middle adulthood stage ages from 40 (or 41) to 64. For a variety of reasons, timeliness on young adulthood cannot be exactly defined—producing different results according to the different mix of overlapping indices (legal, maturational, occupational, sexual, emotional and the like) employed, or on whether 'a developmental perspective... the second era, Early Adulthood, lasts from about age 17 to 45...[or] the socialization perspective Pre-adulthood... the adult era of greatest energy and abundance and of greatest contradiction and stress.' In developed countries, mortality rates for the 18–40 age group are typically very low.
According to Erikson, in the wake of the adolescent emphasis upon identity formation, 'the young adult, emerging from the search for and insistence on identity, is eager and willing to fuse their identity with that of others.