The 2008 financial crisis has changed the structure of banking, generating public distrust in the conventional financial system. An alternative has emerged as a result of this lack of confidence. This alternative is known as ethical banking. A growing number of investors, asset managers, and financial intermediaries have incorporated sustainability considerations into their business practices. This paper discusses the origins of ethical banking and describes its primary characteristics. The goal is to determine whether ethical banking can be as profitable as conventional banking despite only investing in projects based on social values. A comparative analysis is performed to identify differences between an ethical bank (Triodos Bank) and a conventional bank (Banco Santander). The analysis was conducted to study the financial activity of both banks over a four-year period (2012–2015). The balance sheets, profit and loss accounts, liquidity ratios, indebtedness, and returns provided by both banks were analyzed. The results indicate that ethical banking is less profitable than conventional banking. Nevertheless, customers are attracted to the social investments and financial transparency that characterize ethical banking. Over the study period, Triodos Bank experienced a greater increase in the number of employees and the volume of loans and deposits than did Banco Santander. Triodos Bank invests in social and environmental projects. This investment approach makes it less profitable than Banco Santander.