This paper positions trust and cooperation in the context of environmental management in Lebanon. Previous studies indicated increasing environmental problems in this area. The effectiveness of the Lebanese government to address these challenges has been reported to be constrained by large varieties of factors. While ‘trust’ and ‘cooperation’ are referred to in literature, it is not systematically studied in the case of Lebanon. This paper assumes that trust and cooperation are reciprocal by nature. It identifies trust and cooperation as a necessary condition for effective environmental management that requires multi-stakeholder cooperation. Nonetheless, we acknowledge that this trust and cooperation relationship can and has been used by stakeholders to effectively obstruct measures and institutions that could reduce environmental problems. The findings are based on 49 structured and semi-structured interviews with public and private stakeholders plus discussions with citizens. In this study, and from the perspective of public and private sectors, we find that -while cooperation between stakeholders within the public sector, and between public and private sector are considered to be generally weak – trust (or the lack thereof) features less prominent in the explanation for this poor management than expected. On the other hands, respondents state that the extent to which citizens are likely to cooperate in environmental management (in terms of participation in joint activities, compliance with regulations, and adjusting behaviors) is related to trust relations of citizens in the governmental authorities and services they provide.