Turning ages 28 to 43 this year, per Pew Research Center (the definitive source on generations that has nevertheless retired the concept of generational framing), millennials are a generation defined by economic events spanning the dotcom bubble to the Great Recession to the advent of social media. But how old they were when those landed really depends on what period they were born in, between 1981 and 1996. 

While there’s debate over whether microgenerations (or generations as a whole, for that matter) are a real thing at all, there’s no denying there are sub-cohorts of millennials with vastly different experiences of business and culture. All four are important to understand—because, love ’em or hate ’em, they’ve become an economic force.

1981 to 1984: The ‘geriatric millennial’

You might know the OG millennials, turning 40 to 43 this year, as elder or “geriatric millennials.” The term divided the internet in 2021 when leadership expert Erica Dhawan published a Medium article about the microgeneration. This early ’80s cohort, on the cusp of Gen X, was the first to grow up with PCs in their homes but also feels comfortable with TikTok, she wrote. Because they straddle the line between digital native and digital adapter, she believes they can bridge the divide between older and younger workers in the workplace, teaching both traditional body language and digital skills.

Generational researcher Jason Dorsey, president of the Center for Generational Kinetics, tells Fortune this group entered a pretty robust job market—even for those who didn’t graduate from college and got to benefit from more years in the workplace. It was the early 2000s, pre-financial crisis but on the heels of the dotcom bubble burst in the millennium, which saw a mild recession. But unemployment was already declining by the time most of this group began graduating from college.

In this way, the “geriatric millennial” microgeneration is a bit more like Gen X “because they sort of have the wind at their back and had more of a foothold than the segment of millennials right after them,” Dorsey says. While they still struggled with high student debt, this stronger footing put them in a better financial position to pay their loans. This is where he says the “tale of two cities” of millennials emerges. 

1985 to 1989: The Great Recession millennial

The mid-to-late-thirties millennial who graduated into the teeth of the 2007 financial crisis and its lingering aftermath has arguably become the economic face of the generation, known for their rocky road to building a career and wealth. The unemployment rate peaked at 10% in 2009, leaving many millennials hopping around the job market, ending up in jobs they didn’t want or with a gap on their résumé as they waited to find the right job, or any job at all. Dorsey says this could have delayed their job prospects by two to five years.

“You didn’t get the benefit of entering the workforce where you planned, and now you’re competing with all of these people who have more experience and oftentimes better networks. It really does set you back in a meaningful way,” he says. “And that’s a pretty steep mountain to climb. Because every progressive graduating year after that, you’ve got this whole new group of people and the recruiters talking to them instead of you because you’ve been out of work for two years.”

Recession graduates typically earn less for at least 10 to 15 years than normal graduates and can find themselves stuck on a downward economic trajectory, finds research published in the Stanford Institute for Economic Policy Research. It didn’t help recession millennials that the cost of living was rising and they were saddled with student loan debt—but didn’t have the work experience to help pay it down, Dorsey points out.

“This is the same group that was told if you go to college and get good grades, everything’s going to work out, and then they crashed into the Great Recession,” he adds. “They won the bad luck lottery.”

1990 to 1993: The peak millennial

Those turning 33 and 34 this year are the largest age groups in America. There were 4.74 million and 4.75 million of them in 2022, respectively, per U.S. Census Bureau data. These happen to be the millennials born in 1990 and 1991, which the New York Times’ Jenna Smialek deems “peak millennials” (for the purpose of this article, we’re expanding the name of this cohort to encompass the entire early thirtysomething millennial set since they share similar characteristics). 

They started their adult life post–Great Recession when there was a significant ramp-up in the economy, Dorsey says. But, he adds, it didn’t feel that way for many because they were dealing with the snowball effect of student debt and the rising cost of living, particularly with housing. 

That there were so many of them didn’t help. As Smialek points out, the outsize number of ’90 and ’91 babies meant greater economic power but more competition to get into college, get a job, and buy homes, as we saw during the heated pandemic housing market. It makes sense, then, that they’re continuing to follow the larger millennial trend of delaying homeownership, as well as marriage and having kids, which could have implications for future workforces. 

“You end up with the trendline, but you also end up with changing peer pressure,” Dorsey says, explaining that if your friends also aren’t married or haven’t had kids or bought a house, then you might not feel some of the societal pressure previous generations did at the same age. While the oldest millennials were trendsetters around delaying these key milestones, he adds, being in the middle or middle-end of the generation puts peak millennials in a different holding power in which they decide whether this change should be the norm. “You’re not having to be the pioneer of these generational characteristics, but you are deciding which are the ones you want to carry forward.”

1994 to 1996: The cusper millennial

The youngest millennials have a lot in common with the oldest millennials, in that both groups straddle two generations, often referred to as “cuspers.” The mid ’90s cohort has been nicknamed Zillennials for sitting in between the digital-pioneer world of millennials and the digital-native world of Gen Z. But Dorsey says they don’t identify with millennials or with Gen Z, as many of them don’t remember 9/11. 

This gives the group a challenging identity, he adds: “They feel like there’s sort of a bridge or stuck between these two worlds.”

But like their older peers, this creates an opportunity for the youngest millennials to develop unique characteristics that impact the workplace. As Dorsey explains, they often end up in management-leadership type roles “because they’re used to being a bridge between people.”

Of course, microgenerations are more nuanced than the catch-all term they’re intended as. And they aren’t specific to millennials, especially with larger generations like baby boomers. But the characteristics specific to each microgeneration often tend to stick with them as they age, Dorsey says. 

“The events or experiences that created the microgenerations were so formative and impactful that they maintain those differences for a really long time,” he says. “You may lose some of the rougher edges over time, but this is still something that these generations carry with them.”