Background: Oncology outpatients can facesignificant cancer- and treatment-related symptoms that compromise health related quality of life and quality health care. Although the burden of symptoms on patients’ lives are well-known, most health care systems are not ideally set up to relieve them. Patients are not typically drawn into meaningful engagement with the health care team in ways that enable symptom self-management. As a result, opportunities for early identification and treatment are lost, causing avoidable human suffering and cost. The Northwestern University IMPACT (NU IMPACT) project aims to evaluate the effectiveness and implementation of an informatics-driven symptom monitoring and web-based self-management intervention. The project uses PROMIS measures, integrated into the EHR, to trigger response and intervention. This presentation describes the effectiveness-implementation hybrid trial design and measurement of implementation. Methods: NU IMPACT will test the effectiveness and implementation of a system-wide symptom management intervention, across six adult hematology/oncology and gynecologic oncology outpatient clinics at Northwestern Memorial HealthCare, using a cluster randomized pragmatic roll-out implementation trial with an embedded individual-level randomized clinical trial. This unique design allows for a fully-powered randomized trial to establish the efficacy of the intervention, as well as a randomized test of implementation. We are enrolling approximately 6,000 patients in pre-implementation and 6,000 in post-implementation, with half of the latter group randomly assigned to enhanced symptom management, and the other half to usual care. Results: Implementation process is guided by the Exploration, Preparation, Implementation, and Sustainment (EPIS) model with evaluation following the RE-AIM framework. Particular focus is paid to adoption at the clinic and provider levels, the extent to which the intervention achieves meaningful reach to cancer patients, and the potential for sustainment. Additionally, we are testing and validating a newly developed method for tracking and reporting dynamic changes to implementation strategies. Conclusions: Achieving the aims of the NU IMPACT project is a critical step in the advancement of informatics-driven symptom management interventions for cancer patients. The innovative implementation trial design and measurement approach will aid in the rapid translation of findings to other healthcare systems. Clinical trial information: NCT03988543.