The issue of illicit financial flows (IFFs) is at the forefront of the international agenda. Governments worldwide are joining forces to combat money laundering, tax evasion and international bribery, which make up the bulk of IFFs. Although the exact scale of the problem is unknown, IFFs have devastating effects on developing countries. Instead of attempting to quantify precisely what is, by definition, a hidden activity, now is the time to determine where public funds should best be targeted to make the most impact.