Concern about the relationship between trade and the environment has generated a growing debate on the structure of international environmental management. In some instances, this debate has broadened to encompass a general discussion concerning possibilities for strengthening what are becoming increasingly known as "multinational environmental agreements" (MEAs). Such a strengthening is very welcome, indeed overdue. The universe of international environmental agreements presents a highly complex, even confusing picture. Because it is difficult to discern any order in the current pattern, there exists a tendency to postulate an ideal structure for an effective international organization and then to seek to apply that to the MEAs. This paper argues that there are reasons for the current structure of international environmental management and that an attempt to strengthen these agreements must begin with an understanding of why environmental agreements are effective. The paper then summarizes recent developments in research on the effectiveness of environmental regimes. It focuses on the issues of problem structure, institutions and organizations and argues that organizational design should flow from the institutions that are being employed, and that these in turn should display a good fit with the problem structure of an issue.