Theories of associational and deliberative democracy have presented convincing arguments that civil society participation will render governance beyond the nation state more democratic. Empirical research, however, has provided ample evidence that Civil Society Organizations’ (CSO) participation does not live up to expectations in its democratic added value. Apart from deficiencies in equal representation, effective participation in the sense of 'impact on output' is limited due to a lack of IO accountability. Hence, expanding on earlier research on the democratic potential of CSO involvement in EU governance, this project will turn to the role of CSO in fostering EU/IO accountability. It will explore the conditions which enable or constrain CSO to ask international decision-makers to explain and justify their conduct, to pass judgement and make them face consequences.