The Eastern Arc Mountains in Tanzania and Kenya are an ecoregion of great ecological and socio-economic importance. The global significance of this ecoregion is manifested through its role as a carbon sink and as a habitat for a number of endemic and endangered flora and fauna. Despite their importance, the Eastern Arc Mountains are facing significant threats, with an estimated 70% of original forest cover already lost to deforestation and degradation. This briefing explores the threats, policy responses and governance challenges of the Eastern Arc Mountains with a particular focus on Tanzania, where the greater part of this ecoregion is situated.