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When I committed to Princeton, I didn’t realize that I was also securing an invite to one of the largest annual parties in America — for life. Each year, tents engulf dorm courtyards, trolleys shuttle guests through the heart of campus, and as of recent, one unlikely object takes center stage: the cup. At an event where beer is king, cups reign as queen — and they’re evolving.
The turbulent collision of an emerging start-up, a determined student crew, and 170,000 compostable cups in 2023 tells the story of how investments in sustainability can shape Reunions and the world. Reunions is more than just a four-day party. Its sheer scale — and the deep emotional and financial buy-in from alumni — makes it one of the most powerful platforms Princeton has to model and invest in sustainable change.
Princeton already functions as a sustainability incubator in other ways — I know this firsthand from my role with the Office of Sustainability, which utilizes the University’s campus to innovate and test sustainable solutions. As a self-contained community, students can be easily mobilized to be at the forefront of Princeton’s transition to net-zero.
To see what happens when sustainability integrates with the chaos of Reunions, I spoke with Earth Brands co-founder Peter Frelinghuysen. Struck by the reliance on single-use plastic he noticed in college, Frelinghuysen created Earth Cups — a compostable alternative — and first partnered with a handful of Reunions committees in 2022.
When I spoke with him, he told me that by 2023, Earth Brands had scaled up: With backing from nearly every major reunion planning committee, they distributed 170,000 cups and launched its first closed-loop collection system. With the help of a paid undergraduate “Cup Crew,” the company successfully diverted 120,000 cups — 71 percent of those used — toward off-site composting.
On the surface, investing in greener cups at Reunions might seem futile — after all, the average attendee generates 800 kilograms of carbon dioxide just getting there, according to an internal analysis conducted by the Office of Sustainability. While the event itself may be environmentally unsustainable, this effort was far from trivial. For Earth Brands, Reunions presented both the “perfect environment” and greatest “challenge” for proving their product, Frelinghuysen told me. For Princeton, the stakes were just as high. Betting on Earth Brands — a young start-up with a model untested at this scale — posed a significant logistical risk during the University’s flagship annual event.
However, by carefully constructing avenues to support green start-ups like Earth Brands, Reunions can be more than just a nostalgic celebration; it becomes a live lab for the “creative problem solving” aspired to in the Sustainability Action Plan and the global service promised in the University’s unofficial motto.
Earth Brands has since grown into a multi-million dollar company, landing partnerships with Madison Square Garden, Marriott, and American Airlines. But it had its breakout success at Reunions, due to critical support provided by alumni organizers, the student-run Cup Crew, and three tireless staff members from the company itself.
This kind of outcome shouldn’t be a one-off. For green start-ups to flourish and the planet to benefit, Reunions committees — volunteer groups of alumni organized by class year — could budget early for the “green premium” often tied to sustainable products. That financial commitment makes it possible to recruit and pay student crews who support the rollout of new green products and services like the Earth Cup. It’s a virtuous cycle: alumni funding enables student involvement, ethical student labor powers early-stage innovation, and start-ups get a rare opportunity to prove their concepts in front of up to 26,000 people.
There are realities to making this kind of move work. For many students, working Reunions is a highly coveted gig with free housing, generous pay, and early access to the biggest party of the year before they’ve earned the right to a beer jacket. But after speaking with two members of the 2023 Cup Crew, their job wasn’t entirely what they were prepared for.
With only six people on the team, collecting 170,000 cups from dozens of tents and transporting them across campus in just four days was an extreme challenge. Trash bags routinely broke under the weight of beer-filled cups left inside of them. One student recalled needing “three showers a day” to wash off spilled beer and make it through the workday. Another described the challenge of managing new systems in areas filled with intoxicated guests. Their work was messy and exhausting, and neither they nor the University expected how difficult it would be. But it exposed a critical truth: meaningful change takes real labor, and in this case, students were the ones shouldering it.
The Cup Crew was quietly disbanded after its first year — now that Earth Brands is a developed brand, they’ve hired their own workers to staff 2025 Reunions. But its brief existence also highlighted the importance of safeguarding the experience of student workers in the process. If Princeton wants to be a leader in sustainable innovation, it needs to ensure that the students involved are not just enthusiastic volunteers, but properly trained and adequately staffed to do their jobs with safety and dignity.
The path to a net-zero Reunions remains uncertain. But Earth Brands’ story proves that the same university known for beer jackets and century-old traditions can also launch the next wave of sustainable solutions. For alumni organizers investing in green products, the impact may be far greater than they realize. It’s time to leverage Princeton’s most iconic celebration not just to honor the past, but to pilot the future.
Darren Milman ’27 is a SPIA major pursuing minors in Sustainable Energy and Climate Science from Morganville, N.J. He is a student researcher within the Office of Sustainable Energy’s Campus as Lab program, working toward a more sustainable Reunions. He may be reached at darren.milman[at]princeton.edu.
Please send any corrections to corrections[at]dailyprincetonian.com.
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