Illegal logging causes forest degradation and serves as a catalyst for deforestation. Tackling illegal logging is therefore a foundation for conserving forests and biodiversity, reducing emissions from the forest sector, and sustainably managing production forestry. The extent of corrupt and illegal activities in the forest sector is difficult to document, making it difficult to monitor progress. Nevertheless, over the past decade, the adoption of timber legality measures that use third-party verification of legal compliance and involve independent monitors has strengthened the political basis for action. Innovative “transparency technologies” have enabled more effective law enforcement by states, accountability by companies, and oversight by civil society. However, realizing global forest and climate objectives will require enhanced effort and collaboration among these groups.