While thousands of international treaties have been concluded, it remains unclear whether they have been implemented. This article investigates the relationship between the conclusion of environment-related international treaties and the adoption of domestic environmental legislation. Thanks to data sets that are considerably more comprehensive and fine-grained than those previously used, we can analyze the direct link to environmental legislation rather than the less direct link to environmental outcomes. Moreover, we can disaggregate for specific environmental issue areas. Our results suggest a positive relationship between domestic environmental legislation with both international environmental agreements and preferential trade agreements (PTAs) with environmental provisions. This link is more robust for PTAs, mostly present in developing countries, more pronounced before rather than after the treaties’ entry into force, and shows significant variation depending on the issue area. These findings contribute to the literature on environmental regime effectiveness and the domestic impact of treaties.