First, the encouraging news: A record 86% of U.S. employees say they are satisfied in their current jobs, the highest percentage since 2004, reports the Society for Human Resource Management. In particular, they feel respected (72%), they trust senior management (62%), and most (58%) get along well with their bosses. About three-quarters (74%) call themselves “highly motivated” to meet company goals, a jump of 10 percentage points since last year.

Now, here comes the puzzling part: Another survey, this one by career site Monster.com, confirms those warm fuzzies, finding that a 71% majority of full-time employees are happy, or even very happy, with their work. Yet 73% told pollsters they are “thinking about another job.” More than half have updated their resumes in the past three months, and 43% say they are more likely to consider a new job offer now than they were a year ago.

What gives? Money is certainly one sticking point. Despite robust job growth, wage gains so far in 2015 have amounted to a measly 2.2%. “Companies have been focused on productivity, which means many people are working a lot harder than before the recession,” observes Joanie Courtney, senior vice president of global market insights at Monster. “Yet compensation has not kept up. Going somewhere else is one way to earn more.”

Demographics also play a part. Now that Millennials and Gen X together make up two-thirds of the workforce, job mobility seems to be rising. Consider: Fully 80% of employees aged 25 to 44 have worked for their current employer for six years or less. By contrast, 52% of those aged 45 to 54, and 70% of the 55 and over age group have been at one company (although not necessarily in the same job) for six years or longer.

“Millennials are looking for the next new adventure, but older employees are also open to making a change,” says Courtney. “No one stays in one place as long as they used to.”

What’s an employer to do? Keeping Millennials, while also enticing their elders to stick around, takes “a few steps that are very basic, but that busy managers often lose sight of,” notes Courtney. She recommends sitting down with anyone you really don’t want to lose and finding out what their career goals are, with an eye toward helping them get there without having to quit.

Millennials in particular “really want to constantly learn new things, so give them lots of stretch assignments — which doesn’t just mean piling on more work. And everyone craves recognition and thanks,” she adds. “It may also be time to review everyone’s compensation. A raise or a bonus is always welcome.”