This paper investigates the relationship between the financial performance and social performance of microfinance institutions (MFIs) from 10 countries of the Middle East and North Africa (MENA) region. Two models with interacting variables are applied to an unbalanced panel of 67 MFIs, including 18 Islamic ones (IMFIs), over the period 2004-2015. It distinguishes SolebusinessIMFIs granting exclusively Islamic services from Window IMFIs that diversify their services (Islamic and conventional). It tests five assumptions about the controversial superiority of IMFIs over conventional MFIs (CMFIs), with respect to their financial performance and social performance. Results show that MFIs, whether Islamic or conventional, face a financial vs. social performance trade-off. Window IMFIs experience higher financial performance than Solebusiness IMFIs and CMFIs. However, the three assumptions regarding financial performance are unverified. Outreach of the Solebusiness IMFIs differs from that of Window IMFIs and CMFIs. Nevertheless, the two assumptions concerning social performance are also unverified. Hence, there is no evidence that IMFIs exceed CMFIs.