The New York Times

By Patricia Cohen

Baby boomers have long been considered the generation that did not want to grow up, perpetual adolescents even as they become eligible for Social Security. Now, a growing body of research shows that the real Peter Pans are not the boomers, but the generations that have followed. For many, by choice or circumstance, independence no longer begins at 21.

From the Obama administration’s new rule that allows children up to age 26 to remain on their parents’ health insurance to the large increase in the number of women older than 35 who have become first-time mothers, social scientists say young adulthood has undergone a profound shift.

People between 20 and 34 are taking longer to finish their educations, establish themselves in careers, marry, have children and become financially independent, said Frank F. Furstenberg, who leads the MacArthur Foundation Research Network on Transitions to Adulthood, a team of scholars who have been studying this transformation.

“A new period of life is emerging in which young people are no longer adolescents but not yet adults,” Mr. Furstenberg said.

National surveys reveal that an overwhelming majority of Americans, including younger adults, agree that between 20 and 22, people should be finished with school, working and living on their own. But in practice many people in their 20s and early 30s have not yet reached these traditional milestones.

Marriage and parenthood — once seen as prerequisites for adulthood — are now viewed more as lifestyle choices, according to a new report released by Princeton University and the Brookings Institution.

The stretched-out walk to independence is rooted in social and economic shifts that started in the 1970s, including a change from a manufacturing to a service-based economy that sent many more people to college, and the women’s movement, which opened up educational and professional opportunities.

Women account for more than half of college students and nearly half of the work force, which in turn has delayed motherhood and marriage.

Dr. Dora Hughes, 39, married last year and is pregnant with her first child. Dr. Hughes, who works for the Department of Health and Human Services in Washington, said she did not finish her education until she was 30, and so had always expected to marry later on in life. Most of her friends from college waited until their late 20s or 30s to marry as well, she said.

Dr. Hughes, who grew up in Chattanooga, Tenn., said, “My parents got married when they were 24, and my mother always said she thought marriage was hard work and thought it was better for women to wait till their 30s.”

“That probably did have an influence,” she added, since her mother always encouraged her to get an education and have a career.

For the first time, a majority of mothers, 54 percent, have a college education, up from 41 percent in 1990. “That is a huge change,” said Andrew J. Cherlin, a professor of sociology and public policy at Johns Hopkins University.

The median age for a first marriage was 23 in 1980; now it is 27 for men and 26 for women, the highest on record. A recent report by the Pew Research Center found that in the past two decades, a broad trend toward delaying motherhood that stretches across all races and ethnic and income groups has also taken hold.

“I was struck by the fact it increased in all ethnic groups,” said D’Vera Cohn, a co-author of the report, adding that it was evidence of the strength and breadth of this transformation in the life cycles of Americans.

For many, marriage has disappeared as a definition of traditional adulthood, as more and more younger people live together. Today 40 percent of births are to unmarried mothers, an increase from 28 percent in 1990.

At the same time, more women are remaining childless, either by choice or circumstance. Twenty percent of women in their 40s do not have children, Mr. Furstenberg said, pointing out that “not having children would have been considered bizarre or tragic in the ’50s; now it’s a lifestyle choice.”

Laura Tisdel, 28, who grew up in Detroit, said, “I figured I’d either get married in college or right after and basically be a smart mother.”

Instead Ms. Tisdel ended up getting a job offer in publishing in New York City. She said she came close to marrying when she was 23, but then realized, “I wasn’t only not ready to get married to this guy, but I wasn’t ready to get married at all.”

She recently got engaged. Her grandparents thought she was a “lesbian spinster” for waiting so long, she said, while her New York friends think she is too young to be marrying. Her parents, 53-year-old baby boomers who met at 14 and married at 21, told her not to be in a rush.

“The longer I waited to get married, the more reticent I became,” she said. She and her fiancé want children, but feel they are not yet ready. “We’re both nervous about what would be lost,” she said.

More schooling has meant that children have to rely on financial support from their parents. Adults between 18 and 34 received an average of $38,000 in cash and two years’ worth of full-time labor from their parents, or about 10 percent of their income, according to the MacArthur network.

Figures on how much parents spent 20 or 30 years ago are scarce, but Mr. Furstenberg said new research that he and a colleague, Sabino Kornrich, are working on shows that “prior to the 1990s, parents appeared to invest most in children in their teen years.

In the late 1990s, however, parents’ spending patterns began to shift so that the flow of money was greatest when their children were either very young or in their mid-20s.”

More people in their 20s are also living with their parents. About one-fourth of 25-year-old white men lived at home in 2007 — before the latest recession — compared with one-fifth in 2000 and less than one-eighth in 1970.

The sizable contribution from parents not only strains already stressed middle-class and poor families, researchers argue, but could also affect institutions that have traditionally supported young adults in this period, like nonresidential and community colleges and national service programs.

“We have not developed and strengthened institutions to serve young adults,” Mr. Furstenberg said, “because we’re still living with the archaic idea that people enter adulthood in their late teens or early 20s.”