International and transboundary governance is increasingly characterized by the disentanglement from traditional political institutions and the emergence of new, horizontal and dialogue-oriented governance modes. Within the Great Lakes-regime between the USA and Canada, deliberative governance across national boundaries has been evolved, which produces democratic legitimacy and effectiveness through the inclusion of civil-societal and economic actors, argumentative procedures and common good oriented problem solving. This raises a challenging research question: Is the deliberative mode of governance within the Great Lakes-regime a model case, which allows drawing conclusion on institutional prerequisites and means how to âdemocratizeâ governance in similar issue areas? Guided by this research question the paper develops a three-dimensional model (input, throughput, output) of deliberative democracy, which serves as normative-analytical framework in order to identify and to appraise, generally speaking, the potential of deliberative politics in international governance and, in particular, the deliberative potential within the Great Lakes-regime. Equal access to political influence for non-state actors in the political communication and decision making is conceptualized as input-legitimacy. The throughput-proceduralism relies on the communication and action modes between state and non-state actors aiming at collective preference formation. The output-effectiveness relates to the search and formulation of factual and common good oriented problem solving options, which can be recognized by the public as such ones. My long-term empirical study on the Great Lakes reveals that a deliberative network and multilevel governance system of a bilateral decision making body, expert advisory bodies and public participation has been established. Six different public participation procedures on different political-institutional levels have been identified and analyzed by means of an interpretive analytical approach including policy analysis, discourse analysis and speech act analysis: public hearings, workshops, meetings, round tables, focus groups, and public advisory bodies on the regional and local levels. The results of the expert and public participation within a two-years-working cycle are aggregated in biannual reports, which provide the basis of the Canadian and US environmental policy making on the Great Lakes.Against the background of the theoretical-conceptual research on deliberative democracy and the empirical analysis of the Great Lakes-regime, generalizing conclusions can be drawn on the institutional and procedural design of deliberative governance in transboundary and international spaces in form of a loose coupling of decision making bodies, scientific advisory bodies, public participation, and epistemic community. For this purpose the merits and weaknesses of the Great Lakes-regime were carefully considered and the normative thoughts reflected. ..PAT.-Unpublished Manuscript [ABSTRACT FROM AUTHOR]