Consisting of teams working with firm-leve data, the International Study Group on Exports and Productivity has used comparable micro-level panel data for 14 countries and a set of identically specified empirical models to investigate the relationship between exports and productivity. The overall results are in line with the big picture that is by now familiar from the literature: exporters are more productive than non-exporters when observed and unobserved heterogeneity are controlled for, and these exporter productivity premia tend to increase with the share of exports in total sales; there is strong evidence in favour of self-selection of more productive firms into export markets, but almost no evidence in favour of the learning-by-exporting hypothesis. The authors document that the exporter premia differ considerably across countries in identically specified empirical models. In a meta-analysis of the results they find that countries which are more open and have more effective government tend to report higher productivity premia. However, the level of development per se does not appear to offer an explanation for the observed cross-country differences.