Microfinance institutions and other lenders in developing countries rely on the promise of future loans to induce repayment. However, if borrowers expect that others will default, and so loans will no longer be available in the future, then they will default as well. We refer to such contagion...

We analyze lending contracts when social sanctions are used to enforce repayments and borrowers differ in their unobserved sanctioning abilities. Symmetric group loans are preferred to cosigned loans when borrowers are relatively equal, and cosigned loans are preferred when borrowers are...