Biologists and ecologists, medical researchers and EMTs, doctors and nurses, biomedical engineers and neuroscientists came with stories of why they fell in love with science.
They ranged from little girls to seasoned science veterans, all carrying a message of what they'd like to tell other women.
"It's important for women scientists to be here because there are still too few of us," said neuroscientist Sharri Zamore.
She drove from Blacksburg, Virginia, to support the cause, but also to "encourage more diversity" in the sciences, she told CNN.
There were many who stood up and marched for the first time in their lives.
"This is the first time in my adult life that I have been able to stand up for something that I truly believe in. We both felt very passionately about science and the subject of this march, so we decided to drive to DC from Buffalo, New York," said 26-year-old EMT Alyssa Militello, who came with her friend, fellow EMT Jessica Robins, 23.
There were scientists there who paved the way for others, like Cynthia Chatterjee, a psychiatrist and addiction specialist from the Bay Area.
"Historically women have not been encouraged to study science," Chatterjee told CNN. "I didn't go to medical school until I was age 34, but when I was a little girl, I wanted to be a doctor."
It wasn't until much later that she realized she could do it. And now, standing at the science march, she said she hoped other little girls could pursue their dream from the very start.
One of the most common messages for women and for the next generation was: Don't give up. Ever.
"I would tell other female scientists, no matter how hard it may seem, it's absolutely worth it," said biomedical engineering student Remy Cooper.
She said she hopes to help shape science policies someday. Well, after she finishes her Master's and gets into a Ph.D. program, of course.
Other women were more forward with what it's really like to be a woman in a traditionally male-dominated field.
"Know that there is sexism and don't be naïve that it won't affect you. When you need to stand up for yourself, do so," said wetland ecologist Alicia Korol. "Don't be afraid to raise your voice or to speak up for something."
The Ph.D. candidate at George Mason University stressed the importance of finding a fellow female to help chart your career course.
"Mentorship inspires women to stick with or even pursue science. It makes the field welcoming, fun and encouraging," Korol said.
Sometimes, it's not a bad thing to be the only one like you in a crowd.
Lynette Stehr is a Department of Homeland Security contractor and a terrorism risk modeler.
"There's a whole lot of time I am the only woman in the room and sometimes it's a little hard to get used to. But, if you can embrace it and recognize your strut, you're making a pathway for that next woman behind you," she told CNN.
Stehr and her husband, Jeff, were carrying matching signs that read "Listen to your nerds."
While it may be hard to crack into a male-driven workplace, Stehr's husband said he's seeing more of it where he works at NASA, as a contractor.
"I'm mighty proud of just how many women we have been hiring into my team at NASA HQ. It's almost as if we just keep walking by an unguarded gold mine and walking away with awesome hires that other companies just keep missing," he told CNN.
"Their loss is forever our gain. Amazing what people do when you give 'em a shot."