Environmental management standards (EMS) are important voluntary management tools that aim at reducing the environmental impact of firms' activities. From ethical motivations through increasingly high pressure from regulatory authorities to expected financial returns, reasons to adopt an EMS are manifold. While they all certainly matter, it is still unclear from the literature which firm-specific organisational capabilities and structural characteristics significantly drive adoption. Using Propensity Score Matching (PSM) on two samples of French firms, we identify firm-specific factors associated with the early or late adoption of ISO 14001-type EMS and we test whether adoption increases labour productivity. We find that adopters are moderately large manufacturing firms that rely on ISO 9001 standards or Total Quality Management. In addition, according to the first sample, early adopters tend to be more technologically complex firms that are active in the European market. These differences are attenuated in the second sample, which may be biased towards more innovative firms. Both samples however concur with the conclusion that, whether early or late, adoption is associated with a higher labour productivity compared to non-adoption. This result still holds when we use fully interacted linear models instead of PSM, and seems to be consistent over time. Thus, implementing EMS might provide win-win opportunities to adopters, without giving any premium to ''early birds''.Standardisation and industrial regulations have played a major role in improving the quality, safety and reliability of the goods and services that we use today.Organizations implement increasingly technical industrial standards, which are often imposed by policy-setting institutions or through industry-level agreements. Others, though, are non-manda-tory, which raises the question of the determinants of their adoption. This is the case in particular of environmental management standards (EMS) such as ISO 14001.