The German Environment Agency (UBA) has published a report summarizing the contents and outcomes of the October 2017 scientific stakeholder meeting on nanomaterials in the environment. The meeting focused on the relevant regulatory results of recent German and European research projects on nanomaterials in the environment. The stakeholder meeting provided a forum for participants to present the state of the knowledge on environmental nanosafety in a regulatory context, as well as to discuss the scientific results and their regulatory relevance between affected stakeholders. The meeting included key note talks, platform presentations, and poster presentations. A Knowledge Café provided the opportunity for participants to discuss selected topics with regard to environmental safety of nanomaterials in smaller groups. The meeting closed with a discussion on the lessons learned highlighting the outcomes of the meeting from the perspectives of different stakeholders.