Are USAID programs high impact and good value for money? Do they work? Do they generate more results for less cost than if the agency just gave poor people cash? We don’t always know the answers to those questions, but USAID is trying to find out.

The Trump administration has pledged to tie foreign aid more directly to countries’ United Nations (UN) votes, threatening to punish countries who vote against the US position by cutting their foreign assistance. While the administration’s harsh rhetoric marks a shift from the recent pas...