The objective of this work was to show the importance of Financial Institutions as tools to spread social and environmental responsibility through their influence in the market, by adopting sustainable practices and thus conditioning the market by means of its financing and credit policies. For that purpose, a bibliographic research was made on the subject, on the market mechanisms, and on the current legislation related to social and environmental issues, having BNDES as the main example. The research method used was the qualitative descriptive type, and secondary data were used. With the information obtained at BNDES, cross-checkings and further observations were made in order to highlight the mechanisms and policies adopted by the bank. From such observations, we can conclude that BNDES adopts nearly all the mechanisms studied and is committed with sustainability and socio-environmental responsibility. In addition, we can also infer that, if financial institutions actually adopt existing mechanisms and legislation, they can influence and even condition the market towards a more sustainable development. However, this attitude is only the first step and must be perfected, with the participation of the whole society.