Electronic health records EHRs have the potential to improve measurability and quality of care but excess alerting may reduce alert response through alert fatigue. To understand if targeting of alerts to primary care providers PCPs may be of value in decreasing alert fatigue we looked at the extent and accuracy of PCP identification within one organization-shared EHR and providers clinical decision support CDS use. We hypothesized that PCP identification in the system would vary by site would be accurate and that a PCP's response to alerts would be highest during a provider's primary care visits with their patients and lower when seeing a colleague's patients.