PROJECT ABSTRACT Despite the legalization of retail cannabis (i.e., non-medical, “recreational”) in multiple states, there are still no federal regulations for warnings on cannabis products in the U.S. This is troubling because states that legalize cannabis report increased calls to poison control centers, and cannabis consumption has been associated with cognitive impairment, deadly lung disease, and respiratory problems. At the same time, cannabis has therapeutic benefits, including reduced spasticity for multiple sclerosis patients. The fact that cannabis has adverse and therapeutic outcomes has contributed to an environment where substantial proportions of U.S. consumers both over- and under-estimate the health risks of cannabis. This highlights the need for clear, effective labeling regulations to ensure accurate risk perceptions. Despite evidence of the efficacy of health warning attributes (e.g., adding pictures to text), there is limited data on how such warning attributes influence cannabis consumers in the U.S. This proposal will inform how cannabis warning-label characteristics influence cannabis consumers’ (i.e., past 30-day use) attitudes and beliefs, intentions, and problematic cannabis use behaviors by accomplishing the following specific aims: Aim 1: Assess consumer perceptions about draft cannabis warning labels through focus groups with adult cannabis consumers (21+) from legal retail states; Aim 2: Determine how attributes of updated cannabis warning labels affect cannabis consumers’ (21+ from retail states) emotions and perceived risk using a discrete choice experiment (DCE); Aim 3: Use a randomized clinical trial (RCT) to test enhanced warning labels against the existing product labels to determine how exposure influences cannabis consumers’ (21+ from retail states) label reactions (emotion and reactance), attitudes and beliefs (perceived risks and health beliefs about cannabis), and intentions for problematic use (e.g., driving after cannabis consumption) immediately after exposure (Session 1). At 2-week follow-up (Session 2), we will measure message recall and cannabis-use behaviors in the last 2 weeks (i.e., interpersonal conversations about cannabis, cannabis use, money spent on cannabis, quitting attempts, and problematic use), and behavioral intentions (motivation to quit cannabis in 6 months). This innovative proposal includes training activities to ensure that Dr. Massey achieves the following five career goals: 1) Develop expertise in psychological and biological mechanisms of addiction; 2) Receive hands-on training for the development of cannabis warning labels; 3) Learn advanced research methods for warning label research with DCEs; 4) Acquire advanced training in RCTs; and 5) Create a sustainable line of research for future R01 submissions. The mentorship team includes experts in developing and testing warning labels (Hammond, Thrasher, Popova), substance use research (Hammond, Froeliger), cannabis policy (Hammon...