Prescription drug monitoring programs (PDMPs) are databases that track controlled substances at the provider, patient, and pharmacy levels. While these databases are widely available at the state level throughout the United States, several jurisdictions in recent years have mandated the use of these systems by health care providers. This study explores the implementation of mandatory PDMP technology in primary care practice and the effects on treatment of people with possible substance use disorders. Findings are based on 53 in-depth interviews with primary care providers in New York City, collected shortly following the passage of legislation mandating use of a PDMP by health care providers in New York State. Findings suggest that use of the PDMP highlighted tensions between provider stigma toward substance use disorders and the clinical care of people who use drugs, challenging their stereotypes and biases. The parallel clinical and law enforcement purposes of PDMP technology placed providers in dual roles as clinicians and enforcers and encouraged the punitive treatment of patients. Finally, PDMP technology standardized the clinical assessment process toward a "diagnosis first" approach, consistent with prior scholarship on the implementation of emerging medical technologies.