This paper explores lessons for verification in the timber trade in the light of the increasing pressure on timber producer states to guarantee the legality of their production on international markets. The need to attest to the legality of traded goods demands a system to verify the authenticity of the claim, and it is with this aspect of timber policy development that the present article is concerned. The requirements for timber verification are placed in the context of diverse experiences of verification in relation to international treaties and conventions. Drawing on the evidence of such international processes, the topic of verification turns out to be rather more complex than might initially be assumed. Issues that, at one level, appear narrowly technical and specific to the forest sector raise broader questions about political structures and relationships, and forms of public accountability. The paper discusses the implications of this, and identifies a number of principles of verification systems design.