Purpose: While strategies to evaluate the influence of engaging patient partners in research, such as the Patient-Centered Outcomes Research Institute (PCORI) WE-ENACT surveys, are beginning to emerge, a systematic set of measures for assessing the impact of patient engagement in research (PER) on study approaches and outcomes is lacking. This article describes a workshop and process used to identify and develop Critical Outcomes of Research Engagement (COREs). It proposes preliminary measures for assessing the impact of PER on the research process and outcomes of research studies., Methods: A group of 24 researchers and 5 patient partners participated in a PCORI-funded workshop designed to identify key research outcomes and corresponding measures to evaluate the impact of patient-engaged research on those outcomes. Interactive group discussion and synthesis by workshop attendees led to a proposed set of core components of patient-engaged research by each stage of a research study as well as some overarching principles. Postworkshop discussions further distilled the output and considered potential gaps., Results: CORE components identified were: patient-centered, meaningful, team collaboration, understandable, rigorous, adaptable/integrity, legitimate, feasible, ethical and transparent, timely, and sustainable. Existing measures skew more toward measuring the process of engagement and less toward measuring downstream outcomes of patient-partner engagement in all phases of research., Conclusions: Next steps include finalizing measures, pilot testing them with the workshop participants, and building a larger community of practice to further advance this work. The new community plans to create a measurement tool and conduct a study to validate the measures., Competing Interests: Conflicts of Interest None.