The most popular argument against moral realism is the argument from disagreement: if there are mind-independent moral facts, then we would not expect to find as much moral disagreement as we in fact do; therefore, moral realism is false. In this paper, I develop the flipside of this argument. According to this argument from agreement, we would expect to find lots of moral disagreement if there were mind-independent moral facts. But we do not, in fact, find much moral disagreement; therefore, moral realism is false. I defend the argument, explain the empirical evidence that supports it, and show what makes this challenge novel and powerful.