Background: Obstructive sleep apnea (OSA) is a sleep disorder that commonly occurs in Veterans with moderate-to-severe traumatic brain injury (TBI). Untreated OSA increases risk of poor health outcomes including cognitive impairment, declining mental health, poor physical health, and premature mortality. Positive airway pressure (PAP) is the frontline treatment for OSA that effectively reduces the many negative health consequences of the disease. However, adherence to PAP is required to reap the therapeutic benefit. Unfortunately, PAP adherence is poor. Our recent study showed that 68% of Veterans with moderate-to-severe TBI and OSA were nonadherent to PAP therapy. Psychoeducation is part of the standard of care for OSA treatment with PAP, but on its own is insufficient for improving PAP adherence. Alternatives to the standard of care include evidence-based behavioral interventions such as Motivational Interviewing (MI) and Cognitive- Behavioral Therapy (CBT) which have been shown to increase PAP use and improve PAP adherence in persons without TBI. Unfortunately, these evidence-based interventions (designed for cognitively intact individuals) have not been adapted to address PAP adherence in persons with moderate-to-severe TBI, who often require cognitive accommodations. The goal of this study is to test the feasibility of a novel 4-session manualized intervention, designed with cognitive accommodations, and informed by MI and CBT, to address PAP adherence in Veterans with TBI and OSA. Study Aims: Study Aim 1 will test the feasibility and acceptability of delivering the PAP adherence intervention. Study Aim 2 will evaluate the feasibility of outcome and process measures. To date, no treatment exists to ameliorate the adverse consequences of moderate-to-severe TBI. OSA is a treatable health condition that commonly co-occurs with TBI, which is a leading cause of long-term disability. Method: We will recruit 19 Veterans from inpatient and outpatient TBI and sleep clinics at this hospital. Those meeting eligibility criteria (diagnosis of OSA and moderate-to- severe TBI; nonadherent to PAP, able to provide informed consent) will be invited to participate in the 4-session intervention followed by a qualitative interview to inquire about intervention acceptability. Study measures (e.g., symptom severity, sleep quality of life), will be administered pre- and post-intervention. Adherence will be measures via objective data from hospital software which monitors PAP use. Expected Outcomes and Significance: This innovative study will be the first to develop, test, and refine a clinical intervention designed to enhance PAP adherence using cognitive accommodations specifically for persons with moderate-to-severe TBI. If the intervention is shown to be feasible, results from this study will be used to refine the intervention, and in a future randomized control trial, test the efficacy of the adapted intervention versus treatment as usual in improving adherence...