Drawing on different theories of democracy, this article distinguishes three dimensions of democratic legitimacy: political accountability, voice, and due deliberation. The article operationalizes each form of democratic legitimacy and then looks at how these various forms influence the outcomes in governance networks. The authors test this with a survey conducted in the first half of 2010 among respondents in environmental projects/water management projects (n = 166). The analysis shows that democratic legitimacy in general has a significant positive effect on outcomes in governance networks and that voice and due deliberation have a much stronger impact than political accountability.