Illegal logging is an issue of major national and international concern. Combating illegal logging depends on effective enforcement operations to ensure compliance and identify forest crime. Independent monitors have an important role in ‘monitoring the monitors’ and verifying legality. This briefing paper examines the part that external agencies can play in this work. Drawing on a number of recent experiences, consideration is given to the way in which independent monitoring might be structured, and some of the issues which need to be borne in mind when decisions are made as to what forms of monitoring to deploy.