The Aarhus Convention aims to democratize environmental decision-making. Since its adoption 20 years ago, the Aarhus Convention has led to a fundamental change in German environmental administration. This article explores the administrative capacities, organizational structures and enforcement requirements, identifies challenges for environmental authorities and outlines prospects for better implementing the Aarhus Convention. The main challenges are: extended responsibilities for authorities, greater complexity of environmental decisions, increased transparency, more external communication, stricter procedural requirements, extended access to justice and the reduction of enforcement deficits. The success of the Aarhus Convention largely depends on high-capacity administration, which adapts its way of decision-making to these challenges. In addition, substantive environmental law is the foundation upon which the three pillars of the Aarhus Convention rest. Therefore, this article argues that legal instruments and a high level of substantive environmental law are essential for environmental authorities to achieve effectively the objective of the Aarhus Convention.