Prospective Practice-Oriented Research Project - Abstract Coordinated Specialty Care (CSC) disengagement is alarmingly common and compromises the vision of CSC to support recovery in first episode psychosis Few efforts are focused on developing services to prevent disengagement that do not require additional training and implementation burden of community-based CSC programs. The Early Psychosis Intervention Network’s (EPINET) hub-based structure offers an opportunity to circumvent program-level implementation barriers by developing and implementing systems-level strategies to address disengagement. One strategy employs a centralized service, staffed by dedicated professionals working across a hub, to (1) receive and organize referrals, (2) complete ongoing specialized training in engagement science and evidence-based strategies, (3) provide unbiased support when participants’ and/or families’ relationships with a CSC program are poor, (4) re-engage participants in CSC or actively connect them with other services if preferred, and (5) continue contact with those who refuse treatment in case they reconsider. Currently, no hub-based strategy exists to address disengagement. The primary objective of this project is to use participatory research methods within a learning health system research framework to develop and evaluate a hub-based Engagement Navigator Service (ENS) to prevent CSC disengagement. Our central hypothesis is that, once developed, ENS will support more months in treatment and lower disengagement rates than usual care (UC). Our long-term goal is to co-produce a hub-based navigator service to reduce disengagement. We will attain our objectives via the following specific aims: This Prospective Practice-Oriented Research Project entitled Developing and Evaluating a Hub-Based Engagement Navigator Service to Reduce CSC Disengagement proposes to develop a hub-based engagement navigator service (ENS) for participants and families at high risk for disengagement. We will use robust Participatory Research methods to ensure integration of CSC program staff, participants, and family members in developing all aspects of and materials for ENS (Aim 1). We will conduct mixed methods feasibility/acceptability testing in three CSC programs and use this information to guide ENS refinements (Aim 2). This will be followed by a mixed methods hub wide evaluation using a hybrid type I open cohort stepped wedge design to examine feasibility, acceptability, and effectiveness to improve disengagement outcomes and target mechanisms (Aim 3).