As high schools across the country finish up their academic year and teenagers get ready for the summer, there is one thing many of them won’t be doing over the next few months: working at a job.

The number of teenagers who have some sort of job while in school has dropped from nearly 40 percent in 1991, when I graduated from high school, to less than 20 percent today, an all-time low since the United States started keeping track in 1948.

To be sure, some of that can be blamed on a lackluster youth job market, but many teenagers are unemployed by choice. In upper-middle-class and wealthy neighborhoods, in particular, they are too busy doing other things, like playing sports, studying, and following a full schedule of activities booked by their parents.

“Upper-middle class families and above have made the determination that college admissions officers devalue paid work and that if you’re not pursuing a hectic schedule of activities you’ll be less appealing to colleges,” said Ron Lieber, author of The Opposite of Spoiled: Raising Kids Who Are Grounded, Generous, and Smart About Money. “So now we have over-programmed children who are all the same.”

Adults of a certain age all remember their first job as a teenager. I worked in a hospital kitchen filling orders for patients. It was probably the worst job I ever held, but it was the first time I wasn’t surrounded by my peers, so it taught me how to interact with people of all backgrounds and ages. I also learned the importance of showing up on time, keeping to a schedule, completing tasks, and paying attention to details (after all, I didn’t want to mess up a tray for a patient on a specific diet).

Jobs also provide plenty of opportunities for failure. For many teenagers, making a mistake on a job is the first time they hear that they’re not as great as their teachers, parents, and college acceptance letters have led them to believe.

Lieber, who was a babysitter and a lifeguard in high school, said working as a teenager also imparts important lessons about money, the topic of his book. “I can’t tell you the number of times I’ve heard from 22-year-olds who couldn’t understand why their first paycheck after college didn’t include their full salary,” he said.

There are economic and logistical reasons why so few teenagers are working these days. Jobs that once went to teenagers, mostly retail and restaurant jobs, are increasingly going to underemployed adults. Employers are also unwilling to set work schedules far in advance, making it difficult for teenagers to plan a job around other summer activities. Many school schedules are compressed—classes get out later in June and start earlier in August—leaving little free time for teenagers to work over the summer. And many states have increased the age at which teenagers can drive by themselves or at night, often eliminating jobs with late shifts.

“What employer wants an employee who can only work during the day for a few weeks a year?” Lieber asked.

But sometimes teenage employment is discouraged by teachers and parents who worry it will take away from academics. Negative effects of teenage employment appear to be tied, however, not to whether students work, but to how often and how long. Typically, anything under 20 hours a week is safe bet that academics won’t suffer. Indeed, research has shown that students who are employed while in high school or college allocate their time more efficiently and are motivated to study harder in their classes so they can achieve a certain career goal.

What’s more, employers later in a person’s career like workers who had jobs as teenagers. When I talked with hiring managers of new college graduates for my book about the job market after college, many of them told me they could easily pinpoint the new hires who had worked before and those who never did. “First-timers come to the job with a little too much self-confidence, asking what you can do for them,” said Sarah Brubacher, who formerly headed up eBay’s university programs.

In recent years, the term “adulting” has become a popular way to describe the perpetual adolescence that many of today’s young adults now live. Some 25 percent of Americans 25 to 29, for instance, live with a parent, compared to 18 percent a decade ago. If we want our kids to start growing up like earlier generations, we should begin putting them to work as teenagers.