Using a sample of 625 microfinance institutions (MFI) across 40 countries from 2010-2015, we empirically examine the effect of buffer capital on the performance of MFIs and how this effect varies with loan portfolio quality. We find a negative relationship between buffer capital and MFIs’ performance. We further document that loan portfolio quality positively moderates the buffer capital-MFI performance relationship. We demonstrate that the buffer capital-loan portfolio quality relationship does not vary for deposit-taking, profit-making, and regulated MFIs. Our findings shed new light on the value relevance of capital in microfinance institutions. We use a novel approach to evaluate our results in light of the effects of omitted variable bias.