In contrast to existing work which takes an ex-ante approach and looks for policy prescriptions which yield welfare improvements, we take an ex-post approach. We ask whether there are indicators which show whether welfare has risen or not in the wake of a reform. That is, we look for evidence of welfare improvements in outcome space. Necessary and sufficient conditions for welfare improving trade reform are derived. These conditions are shown to be useful in evaluating Free Trade Areas and in reforming Article XXIV of GATT.