Ascensão e queda da imagem de um Brasil ambientalmente responsável: uma análise à luz do arcabouço da diplomacia pública. The dissertation deals with the apparent contradiction in the Brazilian foreign policy analysis literature that highlights the active Brazilian participation in multilateral environmental forums, but also points out its lack of systematicity and contradictions. Public diplomacy is offered as a way out of this contradiction when interpreting Brazilian efforts as communication initiatives aimed at dealing with international pressures that return - after 30 years - in an apparent correlation with the State s abandonment of the country s built image of itself as environmentally responsible. For this, the work uses a combination of qualitative and quantitative methods and an extensive bibliographic review in the fields of Brazilian foreign policy for the environment and public diplomacy.