It was a tweet that brought them together. “Hell hath no fury like a scientist silenced,” Caroline Weinberg, a public health educator and science writer in New York City, tweeted late last month. As a result of worries about the impact that President Donald Trump’s administration might have on scientists, Weinberg’s tweet also floated the idea of a “science march” to highlight the importance of research. Someone suggested she contact Jonathan Berman, a like-minded postdoctoral fellow studying hypertension at the University of Texas Health Science Center in San Antonio, who had already set up a Twitter handle: @ScienceMarchDC.

A few retweets later, “things just blew up,” Weinberg says. Within days, the science march account had more than 300,000 followers and a “secret” Facebook group had more than 800,000 members. And last week, Weinberg, Berman, and a third co-organizer, anthropology doctoral student Valorie Aquino of the University of New Mexico in Albuquerque, officially announced that a March for Science would be held on 22 April in Washington, D.C. Science advocates in more than 100 cities around the world say they will hold allied demonstrations the same day.

The marches will be not just for scientists, but for “anyone who believes in empirical science,” the organizers emphasize on the March for Science web page. The demonstrations are meant to be a celebration of science, they say, as well as “a call to support and safeguard the scientific community.”

But although the march has garnered the endorsement of many prominent scientists and some scientific societies, others have so far remained on the sidelines, cautioning in part that the march could paint scientists as just another partisan special interest in an already highly polarized political climate. If the event is “interpreted as ‘These people who like science are marching against Trump,’ it could politicize science even more and potentially hurt public trust in science as an institution,” says communications researcher Dominique Brossard, who specializes in public attitudes on scientific issues at the University of Wisconsin in Madison.

The debate over the march’s wisdom is just part of the whirlwind that has engulfed its amateur organizers, who have yet to meet in person. “I’ve lost so much weight from forgetting to eat,” Aquino says. In just weeks, the organizers have created a web page, written a mission statement, and established a set of core principles. A donate button on the march’s website has been getting hits despite little promotion, and an online store selling swag had racked up more than $10,000 in sales of $25 T-shirts as of 7 February. The trio has also recruited more than a dozen people to fill a steering committee and key organizing posts. Some 40,000 volunteers are waiting for assignments. And Twitter accounts have sprung up to promote global sister marches in Europe; Canada; Mexico; Puerto Rico; Australia; New Zealand; Hong Kong, China; and possibly Japan (see our interactive map).

The organizers have also been reaching out to established groups for help and support. An alliance with the Earth Day Network, an environmental advocacy group that has been around for some 4 decades, helped cement Earth Day as the march date. Sigma Xi, a research honor society that has some 110,000 members and is based in Durham, North Carolina, announced on 3 February it would be an official partner. The American Association of Physical Anthropologists (AAPA, 1700 members) discovered the march will conflict with the last day of its annual meeting, scheduled for a venue in New Orleans, Louisiana, that is eight blocks from the starting point of that city’s planned march. So AAPA leaders decided to cancel that day’s plenary talk and lead attendees to the demonstration.

Others have suggested joining the march will be a bad idea. And Brossard worries that it will be hard for the science marchers to stay on a nonpartisan message, given the diversity of march allies and participants. Harvard University physicist Cherry Murray, who recently stepped down from her post as director of the Department of Energy’s Office of Science, told Science that scientists might better press their case by encouraging members of Congress to support research funding, and by finding ways to work with the Trump administration, rather than protest against it.

March organizers say it is not either-or. They hope the event will catalyze all kinds of actions in support of science, including lobbying policymakers. But “the time has long passed where it’s OK to stay silent,” says Weinberg, noting that although the march is nonpartisan, getting politicians to pay attention to science in policy is a major goal. “The point of science is getting to the truth and helping us understand the world, and acting as though this has no role in politics is ridiculous.”

(Don’t see your march on the map? Let us know: lwessel@aaas.org)

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