For decades, the nation revolved around baby boomers, the generation more than 75 million people strong, born between the end of World War II and 1964. Now it's the turn of the millennials, who came of age around the start of the new millennium in 2001 and have surpassed the baby boomers as the biggest generation.

Millennials, roughly ages 19 to 35 now, have become the dominant group in the workplace, making up 34 percent of the labor force, according to the Pew Research Center, a public policy research unit of the Pew Charitable Trusts, a foundation based in Philadelphia. Within five years, millennials are expected to account for half of the U.S. workforce as more boomers retire.

Some of the influence of millennials is already easy to spot, as more workplaces include amenities like coffee bars as they replace cubicles with sofas. These tweaks to the office decor are just some of the ways companies are trying to get the most out of the innovative 24/7 pace of a generation that grew up with the internet, hovering helicopter parents and tightly orchestrated lives.

Millennials aren't hanging around for their gold watches, workplace specialists say. Instead, they're entrepreneurial, expecting to change jobs frequently as they search for opportunities, build on their skills and advance their careers, rather than follow a predictable corporate path.

Many already have one foot out the door, according to the consulting firm Deloitte, which surveyed 7,700 millennials last year. Nearly half said they'd like to leave their jobs, citing lack of leadership development and finding themselves overlooked for promotions. Deloitte called the "remarkable absence of allegiance" a serious challenge for companies.

As millennials began moving into the workforce, human resources experts grew concerned about a generation that grew up in an atmosphere in which everyone got a trophy for every effort. They worried they would expect constant praise and constant promotions. Human resources associations regularly hosted seminars on how to handle the unrealistic expectations of an entitled generation of workers.

But corporate America seems to wring its hands every time a new generation comes of age, and such fears about millennials have largely dissipated. Instead, clever companies have taken advantage of the entrepreneurial desires of the generation that grew up watching technical wizards become wildly successful - and wealthy - inventing Facebook and other social media sites.

They're ready to leap from opportunity to opportunity, rather than climbing a corporate ladder like their parents. And in these cases, it doesn't hurt they have higher-than-usual levels of self-esteem and confidence.

Millennials want to make meaningful contributions quickly, like launching new products into the marketplace without kowtowing to corporate bureaucracies, said Scott Steinberg, author of the book "Millennial Marketing: Bridging the Generation Gap." Once that's done, many are off to their next adventure.

What millennials want at work What millennials want Millennials are now the biggest generation in the workplace and their size and influence will grow as baby boomers retire. But many are unhappy, according to the consulting firm Deloitte, which surveyed 7,700 millennials and found nearly half are looking to leave their jobs. Here are some insights into ways companies can attract and retain millennials, according to Deloitte's research: Work-life balance: Millennials want fulfilling professional and personal lives. Companies that help them move into leadership roles while allowing them to pursue their passions will have a leg up. Values: Millennials want to work for organizations that have a purpose beyond profit. More than half have ruled out working for a specific organization because of its values. Mentors: Millennials appreciate the advice and attention to their professional development. New challenges: Millennials are likely to leave if they feel their skills are not being developed or they're being overlooked for leadership positions. What have you done lately?: Millennials are unimpressed by how long a business has been around. What matters is the quality of a company's products and services today.

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Sometimes that means millennials might go from leading organizations to joining startups. That may seem risky to older co-workers but logical to millennials focused on building skills rather than measuring success based on the number of subordinates they manage.

"They want to hop their way up the ladder," Steinberg said.

Millennials, who grew up with the constant connection and instant response of social media, prefer direct contact with their managers and regular feedback, said Caitlin Porter, assistant professor of industrial organizational psychology at the University of Houston. They want to know how they're doing and how they can progress.

The desire for frequent chats is an adjustment for older managers, whose own experience taught them that if the boss wanted to talk, something was wrong, said Jason Dorsey, co-founder of the marketing and employment consulting firm Center for Generational Kinetics in Austin. Millennials want expectations laid out in advance, on matters both small and large, Dorsey said.

If a company's dress code is business casual, explain what business casual means, he said. Even better, show photos or videos.

A lot has been made that millennials don't care about money as they pursue excitement and opportunity. But that's not true for the generation that has racked up more college debt than any other. Like everyone else, millennials want to be well compensated for a job well done, Steinberg said.

And they want money to pursue their passions. Instead of the hunker-down, live-to-work mentality pervasive among both pre-World War II and postwar generations, many millennials have embraced a work-to-live ethic. Money is good, but so are the time and flexibility to enjoy their lives outside of their careers.