Mainstreaming adaptation to climate change in forest-relevant policy can be as a "most difficult" case, relevant for asking the question to exent to which adaptation can at all be mainstreamed in complex multi-level governance systems. This study examines the case of to what extent EU and national (exemplified by Swedish) legal and policy frameworks are able to integrate with each other in ways that may support climate change adaptation in forests. To move as close to the real life situation of mainstreaming challenges as possible, the study focuses on not only one area of mainstreaming or integration, but on the three broad policy areas: a) adaptation per se; b) forest biodiversity and habitat protection with respect to invasive species; and c) water protection in relation to forest use.  The study concludes that conflicts between international legal principles such as precaution and free trade, as well as distribution of competences at EU and national level, results in a great discrepancy in terms of opportunities for a nation to effectively act independently as well as for effectively integrating adaptation aims in the connected EU-national systems.