And if they go to college, most of them struggle to finish, or don’t at all. There are 12.5 million 20-somethings with some college credits and no degree, by far the largest share of the 31 million adults who leave college short of a degree, according to the National Student Clearinghouse. In many ways, these young adults are no better off financially than high-school graduates who never attempted college at all. Employers, after all, don’t advertise they want “some college.” They want a degree.

The longer life expectancy for children born today means that we can chart new routes to adulthood that space out opportunities in different ways. We no longer should think of college as one physical place we go to at one time in our lives — i.e., age 18. Yet educators continue to press on families a one-size-fits-all route. It’s almost impossible in our hypercompetitive culture to think differently as a parent about when a college education should happen. The result: Finding a pathway to a fulfilling career and a meaningful life has become much more difficult than it ever should be.

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In Dr. Settersten’s critical thinking class at Oregon State University, the classroom conversation on the day of my visit wandered to a discussion of what the students, mostly seniors, wanted to do next in life. Many said they planned to go on to graduate school.

Dr. Settersten asked how many of them knew their professors well enough to request a letter of recommendation for the application. Only a smattering of hands went up. He wondered aloud: Why hadn’t more of them visited him during office hours, an easy way to build a one-on-one relationship with a professor who teaches hundreds of students a semester?

“What shocked me is that they say, ‘No one has told me this before,’ ” he said to me later. “They’re seniors and they don’t know how to navigate the institution.” Fewer than half of college seniors in the annual National Survey of Student Engagement said they talked often with a faculty member about their career plans.

Dr. Settersten’s research focuses on what it means to become an adult today. Unlike many parents and pundits, he doesn’t worry as much about the longer runway to adulthood, arguing that the timetable is more gradual and varied than it was 50 years ago. The traditional markers such as marriage and parenting are now the culmination of adulthood rather than the start of it.

I asked about the somewhat clueless students in his class; doesn’t he worry about them? “Sure,” he said. “When I think of adult life, one of the hallmarks of it is that it’s not predictable.”