Inclusion Criteria:  Veterans aged 18-65 enrolled in VA healthcare and eligible for VA PTSD psychotherapy current diagnosis of PTSD based on CAPS-5 English language fluency willingness to participate in individual, in-person or telemental health PE psychotherapy including use of a mobile device  Exclusion Criteria:  neurological conditions (based on review of the volunteer's medical record) that are severe enough to interfere with PE treatment and assessments (i.e., diagnosed Major Neurocognitive Disorder, severe neurological disorders (e.g., ALS), and those with severe TBI history). Neurological disorders that may result in mildly impaired cognitive function (such as multiple sclerosis or those with history of mild or moderate severity TBI) will be eligible, pending a score of 6 or higher on the Short Portable Mental Status Questionnaire current intent to suicide behavioral patient record flag in the VA medical record a history of a serious mental health condition listed in their medical record problem list that is known to include psychotic symptoms, such as schizophrenia or a depressive disorder with psychotic features. We will also ask for self -reported indicators of psychosis, using an existing interview template in an ongoing threatening situation (e.g. domestic violence) positive screen for severe alcohol use disorder, as indicated by an AUDIT score equal to or higher than 13 or 15 for women and men, respectively prior history of 3 or more sessions of PE therapy for PTSD other current psychotherapy for PTSD that is recommended (with at least weak strength) in the VA/DoD Clinical Practice Guideline for the treatment of PTSD a physical condition that interferes with the proper use of a mobile device. not stable on psychotropic medications for at least 6 weeks prior to enrollment