PCORnet, the Patient-Centered Outcomes Research Network, is comprised of health systems and health plans that transform electronic health records (EHRs) and claims data to a common data model (CDM) to facilitate real-world clinical research. Because patients receive health care in multiple care delivery settings, linking health records across systems and health plan claims would provide a more comprehensive and accurate picture of health care for patients. The current study expanded on a PCORnet Antibiotics and Childhood Growth (ABX) study to (1) identify and implement a privacy-preserving patient linkage solution among a clinical data research network and a health plan network within the ABX Study, and (2) assess overlap in prescribed and dispensed antibiotics and additional data gained from claims among the linked patients. This manuscript describes the linkage process and resulting overlap analysis. The authors identified 549 patients from the EHR record study cohort who had claims records with the health plan. Sixty percent (n = 329) of patients had consistent antibiotic exposure data across the 2 sources, indicating antibiotic exposure (44.3%) or nonexposure (15.7%). Among total antibiotic prescribing records, 43.1% had a matched claims record for dispensing within 60 days. Among antibiotic dispense records 26.5% were not associated with a prescribing record in the linked health systems. These findings showcase the feasibility of linking health plan claims data to PCORnet CDM in a privacy-preserving manner while also demonstrating continued gaps in data that may occur. The study highlights the importance of combining multiple health data sources for comprehensive clinical research.