PROJECT SUMMARY There is much concern by many within public health and medicine, and among policy makers, regarding the increasing use of electronic nicotine delivery systems (ENDS) by youth given the known risks of nicotine on neurodevelopment and growing evidence of other potential health risks of ENDS use. Since the Food & Drug Administration (FDA) announced its final Deeming Rule, ENDS have been deemed a tobacco product and are now subject to several new regulations, among which include a new warning statement requirement for ENDS products and advertisements that will take effect in August 2018. However, the limited empirical evidence of the impact of the ENDS warning statement on perceptions and use of ENDS presents a critical barrier for the FDA in conducting an accurate Regulatory Impact Analysis (RIA) for its ENDS health warning statement requirement. Therefore, the goal of this project is to address this critical barrier by evaluating the effects of the required FDA Deeming warning statement on the likelihood to purchase ENDS among youth and young adults, and whether this effect depends on ENDS flavor. The objective is to conduct a behavioral economic experiment with U.S. youth and young adults to address three aims to examine: (1) the effects of the presence of ENDS warning statement on the willingness to purchase ENDS and intentions to use ENDS among youth and young adults; (2) if the effect of warning statement on willingness to purchase is mediated by risk perceptions of ENDS; and (3) whether product flavors and individual difference factors (e.g., demographics; tobacco use) modify the effect of ENDS warning statement on risk perceptions, intentions to use, and willingness to purchase. These aims will be accomplished by an online experiment in which 900 youth and young adults sampled to be representative of the US population of 16-25 years old are randomized into conditions varying according to the warning statement (no warning statement, FDA warning statement, and MarkTen warning statement) and ENDS flavor (tobacco, menthol, and fruit flavor), and are asked to complete a hypothetical purchase task. This proposed research addresses FDA Center for Tobacco Products (CTP) research priorities of understanding the impact of economics and policies on tobacco use and perceptions (how is youth tobacco use changing in response to FDA regulatory actions).