PROJECT SUMMARY The opioid epidemic in the United States is a public health crisis stemming from prescription opioid use, accessibility to potent synthetic opioids, and alarmingly frequent unintentional fatal overdoses. Chronic pain significantly contributes to this crisis, affecting over 100 million citizens in the United States, surpassing the incidences of diabetes, heart disease, and cancer. Moreover, prolonged use of prescription opioids for pain management markedly escalates the likelihood of heroin initiation and the development of opioid use disorder (OUD), with approximately 10% of patients with chronic pain eventually developing OUD. It is imperative to address these risks by investigating factors contributing to the reduction of prescription opioid use, potentially leading to a decline in adverse health outcomes, instances of OUD, and unintentional fatal overdose cases. Non-opioid treatments, including cannabis and cannabinoid-derived products, are increasingly considered for chronic pain management, with over 24 million United States citizens using cannabis for its analgesic properties. Although clinical trials indicate a significant analgesic effect of cannabinoids compared to placebo, there remains a scarcity of research on effectiveness and potential negative consequences. Moreover, the expanding legalization of medical and recreational cannabis in the United States presents novel opportunities to explore the relationship between opioids and cannabis use in patients with chronic pain. However, notable constraints limit early evidence from studies on opioid and cannabis use in patients with chronic pain, including recall bias, which affects cross-sectional data analyses. Consequently, the existing literature inadequately addresses the factors related to chronic pain that influence opioid and cannabis use in these patients. Intensive longitudinal studies with ecological momentary assessment may address these limitations and offer valuable insights into the mechanisms facilitating opioid and cannabis use for chronic pain. In the current proposal, I have designed a mixed-methods study to expedite the development of interventions targeting the negative consequences of opioid and cannabis use among patients with chronic pain. This project entails advanced secondary quantitative analyses of real-time smartphone-based ecological momentary assessment data from my primary sponsor’s NIDA R21 (R21 DA048175; PI: Thrul). Then, I will conduct an original semi-structured interview-based qualitative study using purposive maximum variation sampling of local expert substance use clinicians working with patients with chronic pain who use cannabis and opioids for their analgesic properties. This project establishes a foundation for intervention development for patients with chronic pain at risk of consequences from cannabis or opioid use; it also aligns with NIDA's primary objective of determining the impact of substance use and addiction on individ...