The National System of Conservation Units was established in Brazil, in July 2000, through Federal Law 9985. This legislative instrument defined different categories of environmental conservation units, in attempt to preserve them and regulate their sustainable use and management. Among the main innovations it comprises, the main aspect that should be pointed out is the fact that it ensures the participation of members of society in general as well as the collaboration of non-governmental organizations, enterprises and individual community members in implementing and managing such units. The city of Rio de Janeiro encompasses different types of conservation units, reporting to different governmental spheres; however, most of them belong to the category of parks. Recent academic studies, reports from auditing organizations that analyzed some of these parks and the press itself have revealed that state institutions have not been successful in their efforts of implementing more collaborative and participative management, in establishing productive partnerships and in assuring the sustainability of these parks. The present exploratory research of qualitative nature aims at analyzing the implementation of collaborative strategies in environmental parks and their effect on the results obtained by management, as well as the nature of the relationships set with the different social players involved. Management problems and the intervening factors that have helped or hindered the sustainability and conservation of such parks are also studied. Multiple case studies were used in the study: six municipal conservation parks managed by the city of Rio de Janeiro, one state park owned by the state of Rio de Janeiro and one federal park. Data were collected from the managing departments of those parks and from representatives from the different categories of stakeholders, including not only those involved directly in managing the parks but also those interested in the parks as users. Based on documentation, direct observation and semistructured interviews, the cases were analyzed individually and collectively, through cross-analysis, to identify common patterns of strategy implementation, successful practices and underlying problems. The findings revealed that governmental agencies have been making an effort to establish more participative management by means of councils, yet these management boards had not actually been implemented at the time of this research. The process of organizing and conducting such councils is slow and inefficient, and can cause controversies among social players and the management teams. The diversity of social actors and intervening factors such as lack of funds, economic and political pressures, uncontrollable urban growth and violence can be aggravating issues. The cases have shown different forms of partnership maintained with varied organizations - ranging from informal to complex; involving multiple actors and even different governmental powers. Factors such as bureaucracy, lack of management autonomy and the inadequate use of managing tools can be barriers to the expansion of such collaborative strategies. As a result of the findings, it was possible to devise a model of the interactions disclosed in the cases studied and a series of theoretical principles to explain how collaborative strategies are influenced by the different factors and how these strategies can affect the success of park management procedures. This model can be groundwork for future research.