This article examines the participation of civil society organisations (CSO) in the various arenas of global governance with focus on the International Organization for Standardization (ISO). While diverse studies recognise the difficulty of CSOs’ participation despite the growing importance of standards in the organisation of markets, little attention has been paid to how such involvement is likely to be reinforced in what we call ‘technical diplomacy’, the negotiating processes involving states and non-state actors geared toward setting specifications claiming to be based on scientific knowledge. Drawing upon scholarship in new forms of regulation in organisational studies, international relations, and science and technology studies, the paper argues that CSOs’ participation depends on multiple translation practices between lay- and expert-knowledge. Findings are based on an action-research project, INTERNORM, pooling academic and CSO participation in ISO technical committees. It suggests some promising directions for addressing the democratic deficit of technical diplomacy.