Where can a dollar improve the most lives? That’s the question guiding GiveWell, a nonprofit that last year directed over $400 million to interventions like malaria medication and lifesaving vitamin A shots. 

Elie Hassenfeld co-founded GiveWell at 25. Then working at a hedge fund, he and a colleague, Holden Karnofsky, wanted to donate money but were “shocked by how little useful information was available,” Hassenfeld says. So they quit their jobs to do for charities what they’d done for investors: dig into the numbers. 

Founding an organization that implied much of charity was wasteful "pissed a lot of people off," Hassenfeld concedes. "I don't think it was the right tone." True to form, GiveWell—which prides itself on transparency—lists “tone issues” among the errors on its public "Our Mistakes" webpage. 

Even so, Hassenfeld can’t help but shoot straight. Over a thousand children die from malaria each day. “That could be front page news… except that it happens every day so it doesn't get reported,” he says. “You wouldn't sell too many magazines if that was your cover every time.” That candor may rub some the wrong way, but it's precisely why GiveWell’s donors—including large-scale funders like Dustin Moskovitz and Cari Tuna—trust him. 

GiveWell used to direct most of its money to a small group of charities it holds in high regard, including the Against Malaria Foundation and Helen Keller International. But as its research team has grown, GiveWell has diversified; 74% of grants now go to cost-effective programs outside its list of top charities. 

Hassenfeld was in Kenya a few years ago where he met a girl—roughly the age of his own children—who’d received a malaria vaccine thanks to GiveWell’s funding. “I was actually surprised that this experience was so moving for me,” he says. He knew the statistics, but a single child’s vaccination card hit differently: money, just as he’d hoped, well spent.