Formal banks rarely serve the rural poor. Microfinance has filled part of this gap, but lenders’ ability to keep costs low and continue extending credit to the poor depends in part on their ability to encourage repayment from borrowers who typically lack adequate collateral or verifiable credit histories. Lenders may use “dynamic incentives,” such as the promise of larger loans or the threat of future credit denial, to elicit timely repayment and lower lending costs. These dynamic incentives, however, work only when borrowers can be consistently identified. In countries lacking formal identification systems, borrowers may avoid sanction for past default by simply applying for new loans under different identities or from different institutions. This can raise the cost of lending by allowing for more default, and the response of many lenders has been to limit the supply of credit and increase its price, which affects many credit-worthy smallholder farmers who cannot finance crucial inputs such as fertilizer and improved seeds. Can biometric identification technology, such as fingerprinting, encourage borrowers to repay their loans and enable financial institutions to grant more loans to creditworthy applicants, reducing the costs and risks of lending? Researchers Xavier Giné (World Bank), Jessica Goldberg (U. Michigan), and J-PAL affiliate Dean Yang (U. Michigan) implemented a randomized evaluation to test this question. The evaluation introduced a fingerprinting system among randomly selected smallholder paprika farmers receiving microfinance loans for subsidized farming inputs in Malawi. Researchers then measured whether borrowing behavior, such as loan repayment rates, changed in response to the identification system.