This paper uses a gravity model to assess ex-post regional trade agreements. The model includes 130 countries and is estimated with panel data over the period 1962-1996. The introduction of the correct number of dummy variables allows for identification of Vinerian trade creation and trade diversion effects, while the estimation method takes into account a potential correlation between some of the explanatory variables and the bilateral specific effects introduced in the model, as well as a potential selection bias. In contrast to previous estimates in cross-section, results show that regional agreements have generated a significant increase in trade between members, often at the expense of the rest of the world.