This paper examines how accountability is practiced by nongovernmental organizations (NGOs). Five broad mechanisms are reviewed: reports and disclosure statements, performance assessments and evaluations, participation, self-regulation, and social audits. Each mechanism, distinguished as either a "tool" or a "process," is analyzed along three dimensions of accountability: upward-downward, internal-external, and functional-strategic. It is observed that accountability in practice has emphasized "upward" and "external" accountability to donors while "downward" and "internal" mechanisms remain comparatively underdeveloped. Moreover, NGOs and funders have focused primarily on short-term "functional" accountability responses at the expense of longer-term "strategic" processes necessary for lasting social and political change. Key policy implications for NGOs and donors are discussed. © 2003 Elsevier Science Ltd. All rights reserved.