This policy paper makes three key recommendations to European governments and global social media companies based on data collected during the Countering Lone-Actor Terrorism project undertaken by a consortium of partners (RUSI, Chatham House, Leiden University and the Institute for Strategic Dialogue). This research brought to light the significant threat posed by right-wing lone-actor terrorism, as well as the need to continue infiltration and monitoring of violent extremist groups. The paper also recommends that social media companies continue to improve user-based reporting systems to expedite responses in potential cases of lone-actor terrorism.