Abstract We examine the impact of biometric monitoring devices placed in tuberculosis treatment centers in Indian slums. The devices record health worker attendance and patient visits. Combining survey data, random center visits, and hospital registers, we find that patients at biometric-equipped centers are 25% less likely to interrupt treatment, reflecting increased efforts by health workers and greater daily adherence by patients. The technology also improves the quality of public data by reducing overreported patient numbers and underreported treatment interruptions. Overall, our results suggest that real-time monitoring of service delivery can strengthen the state’s capacity to serve poor and marginalized populations.