The goal of this chapter is to analyze the effect of the recent global financial crisis on the efficiency of microfinance institutions (MFIs). The double-bottom line of MFIs is considered through the assessment of two distinct efficiency indices. On the one hand, the financial efficiency measures the financial revenues compared to the costs disbursed to generate them. On the other hand, the social efficiency measures the social outreach compared to the costs deployed to provide microfinance services to the poor. The study employs the DEA-based Malmquist Productivity Index methodology to assess the change in efficiency between two time periods. Using a dataset composed of 362 MFIs between 2005 and 2011, the results suggest a decline in both dimensions of efficiency during the crisis. The deterioration was the most marked for commercial MFIs that are closely connected to developed financial markets. The sources of deterioration were mainly related to regression in management practices rather than scale.