Transnational civil society organizations (CSOs) are often said to lack accountability. Taking issue with this claim, we report the results of a study on the accountability regimes of 60 transnational CSOs engaging in political advocacy. We scrutinize their transparency, opportunities for internal participation, evaluations and self-regulation, complaint procedures, and their independence from the state and intergovernmental organizations. We find that most transnational CSOs are reasonably transparent and offer participatory opportunities at least for members. They are organizationally independent from states and intergovernmental organizations, but dependencies on public funding are striking in some cases. Independent evaluations of their activities are scarce and codes of conduct, often suggested as an avenue towards better self-regulation of CSOs, do not seem to play a major role in practice. We conclude that the debate over transnational CSO accountability should focus on the most critical issues. In the case of general interest organizations, this seems to be the danger of co-optation through public financing. Special interest organizations, by contrast, are highly independent but have deficits in external transparency, especially regarding their budget.