Purpose: This paper summarizes the findings of a research project aimed at benchmarking the environmental sustainability practices of the top 500 Mexican companies. Design/methodology/approach: The paper surveyed the firms with regard to various aspects of their adoption of environmental sustainability practices, including who or what prompted adoption, future adoption plans, decision-making responsibility, and internal/external challenges. The survey also explored how the adoption of environmental sustainability practices relates to the competitiveness of these firms. Findings: The results suggest that Mexican companies are very active in the various areas of business where environmental sustainability is relevant. Not surprisingly, however, the Mexican companies are seen to be at an early stage of development along the sustainability "learning curve". Research limitations/implications: The sample consisted of 103 self-selected firms representing the six primary business sectors in the Mexican economy. Because the manufacturing sector is significantly overrepresented in the sample and because of its importance in addressing issues of environmental sustainability, when appropriate, specific results for this sector are reported and contrasted to the overall sample. Practical implications: The vast majority of these firms see adopting environmental sustainability practices as being profitable and think this will be even more important in the future. Originality/value: Improving the environmental performance of business firms through the adoption of sustainability practices is compatible with competitiveness and improved financial performance. In Mexico, one might expect that the same would be true, but only anecdotal evidence was heretofore available. © Emerald Group Publishing Limited.