The U.S. Deprescribing Research Network is a collaborative research network that aims to support investigators and research studying deprescribing for older adults. Currently, 4 healthcare systems are going to participate in a workgroup to demonstrate approaches to using routinely available electronic health data in trials of deprescribing. We are seeking a 5th site to join this workgroup. In this 24-month project, sites will explore existing electronic health data to implement key measures needed for deprescribing studies. We hope this additional site could represent a diverse older adult population, including diverse racial or ethnic groups, people who are economically disadvantaged, or other groups that are often underrepresented in research. This work will provide “proof of concept” demonstrating ways that key measures can be operationalized across different health systems and result in a guide to support multisite collaborations in deprescribing research.