The aim of this thesis is to test whether incorporating principles of responsible investment will have an impact on financial performance when investing in emerging markets. A developed market is included to bring up potential structural differences between emerging and developed markets. Principles of responsible investment suggested by the UN concerns environmental, social, and governance (ESG) issues. The financial performance of highly rated ESG portfolios was evaluated by using the capital asset pricing model (CAPM) and the Fama French 3-factor model. Alpha has been used as the performance measurement. Results reveal that incorporating principles of responsible investment by using a best-in-class approach generates statistically significant and positive alphas in emerging markets, while the developed market of the U.S generates an insignificant alpha.