PROJECT SUMMARY/ABSTRACT Opioid Use Disorder (OUD) is a chronic, recurring condition that if left untreated, poses a significant and ongoing public health threat. OUD is associated with significant impairments in physical and psychological health including increased mortality and high utilization of emergency medical care as well as increased risk of Hepatitis C and HIV infection and Neonatal Abstinence Syndrome (NAS). OUD is also associated with increased justice and child welfare systems involvement. Currently, the number of empirically supported behavioral interventions for the treatment of OUDs is limited, the majority of which cannot be tailored (customized) to meet the unique needs of the individual client. As such, the relapse rate for individuals with OUDs remains high. Virtual reality cue exposure (VRCE) has shown considerable promise in addressing substance craving, one of the most salient components of OUD. Through repeated exposure to substance use cues within a controlled virtual environment, over time these virtual exposures weaken the relationship between substance use cues and craving, potentially leading to decreased substance use and lower probability of substance relapse. Unfortunately, currently available commercial VR products lack the essential ability to easily and repeatedly update exposure environments to introduce novelty or incorporate new or evolving substance use cues. This limitation results in less user engagement over time, potentially leading to user disengagement and premature treatment termination. This research aims to improve upon currently available commercial virtual reality (VR) products designed to address substance misuse by developing a novel subscription-based software product (Helix) that supports ongoing customization of virtual reality-based cue exposure (VRCE) environments resulting in a tailored intervention addressing substance craving. Using measurable benchmarks on standardized assessments of usability and acceptability and informed by feedback from focus groups of key stakeholders, the Helix software will continually be refined until satisfactory levels of usability and acceptability are achieved. This software will also be evaluated to determine if it is feasible for use in both residential and outpatient substance abuse treatment settings.