In an interdependent and interconnected world, countries’ ability to achieve the Sustainable Development Goals (SDGs) is affected by positive or negative spillovers from other countries. International SDG spillovers are pervasive. They can relate to the environment, socio-economic factors, finance and governance, and security. Yet, monitoring of progress towards the SDGs and national strategies largely ignore such spillovers. This working paper describes international SDG spillovers and reviews techniques for their measurement. It proposes six practical steps to close knowledge and data gaps on trade-related international spillover effects.