Russia’s large-scale aggression against Ukraine on 24 February 2022 has forced millions of Ukrainians to flee the country. This historic mass outflow, unseen in Europe since World War II, has sparked an unprecedented mobilisation of institutions and host communities in OECD countries to offer support. Effective communication constitutes an essential tool for co-ordinating this crisis response, enabling Ukrainian refugees to access relevant information about their rights and services provided to them, while also helping to prevent particularly vulnerable migrants from becoming victims of human trafficking and other crimes. In parallel, many hosting countries have used targeted communication to co-ordinate individual and civic society support and to inform the public about crisis responses, migration and integration policies. This policy brief examines communication strategies and best practices across the OECD countries in the current crisis context, drawing from results of a series of OECD NETCOM meetings.