This chapter examines the different strands of literature about ESG factors. First studies on the relationship between financial performances and ESG factors can be traced back to the beginning of the 1970s. However, the increasing attention of investors has prompted the academic literature to investigate the ESG impact at financial and corporate levels. Starting with a new paradigm of company able to embrace contemporary economic dimension together with environmental and social ones, we deepen the main contributions on ESG issues. Therefore, we introduce firstly studies that attempted to assess how ESG factors can impact the cost of capital, both equity and debt, and Firms’ Performance. Finally, we consider financial studies which have attempted to identify the benefits related to ESG investment choices.