One afternoon in the spring of 2008, two graduate students, Michael Faye and Rohit Wanchoo, met with a Harvard Business School professor in an office in Cambridge. They had a simple idea for a charity: Instead of giving poor people food or cattle or loans to start a business, why not simply give them cash?

Eight years later, their idea has become GiveDirectly, a multimillion-dollar nonprofit that donates money directly, via mobile payment services, to poor people in Kenya and Uganda. In 2015, the organization raised more than $50 million.

GiveDirectly’s success mirrors a broader shift toward cash in the humanitarian industry—a shift that could revolutionize a sector that many call out of touch and inefficient. Think of Haiti, where, after the January 2010 earthquake, the Red Cross raised almost half a billion dollars yet built just six permanent homes.

Cash has emerged as a cheap and effective alternative to traditional forms of aid. Jim Kim, the president of the World Bank, has called the results of cash transfers “astounding.” Last year, Great Britain’s Department for International Development (DFID) funded a report that came to an unequivocal conclusion: “Give more unconditional cash transfers.”

Yet for all the hype, cash makes up only 6 percent of global humanitarian spending, or about $1.2 billion in 2014. This number includes aid given in the form of vouchers, however, so the real number is probably closer to just 2 percent. Big players in the aid industry, particularly NGOs, have pushed back against cash transfer programs, seeing them as a threat to their way of doing business.