ABSTRACT People with HIV/AIDS (PWH) are twice as likely to smoke cigarettes compared with the general population. Further, PWH are less likely to quit smoking, likely due to barriers including co-occurring behavioral risk factors, stigma, limited resources, experiences of racism and discrimination, and diminished access to health care. Importantly, cigarette smoking is a significant risk factor for both HIV-related and non-HIV-related morbidity and mortality among PWH. Health disparities observed among smokers with HIV are compounded by the tendency for PWH to have lower incomes, lower education attainment, and lower access to healthcare. Suboptimal rates of smoking cessation and HIV disease management among Black PWH who smoke appear to be related to increased exposure to interoceptive- stress symptoms (e.g., anxiety, bodily sensations, stress-related burden due to racism or HIV diagnosis discrimination or stigma). Consequently, smoking cessation interventions and HIV disease management directed toward Black PWH who smoke might benefit from a specific focus on decreasing emotional reactivity to interoceptive stress. Anxiety sensitivity (AS) is a candidate mechanism pertaining to the expectancy that interoceptive sensations are personally dangerous, which escalates emotional reactivity. Yet, only one study has leveraged the potential of AS to better understand smoking, HIV disease management outcomes, and interoceptive stress relations among Black PWH who smoke. Our group, along with collaborating colleagues, has developed smoking cessation interventions for PWH that engage AS to increase smoking cessation success. Early work included in person smoking cessation interventions. Our more recent efforts have focused on developing and testing an integrated, culturally appropriate, mHealth intervention for smoking cessation, AS reduction, and HIV disease management improvement for Black PWH who smoke (MASP+). MASP+ targets multiple health conditions that interfere with successful aging: smoking, mental health, and HIV disease management. To date, MASP+ has only been available to patients receiving HIV care within a single, urban community clinic. This proposal aims to test MASP+ in a national sample of participants with treated and untreated HIV. First, we propose to review already developed MASP+ materials with 30 members from our priority population to ensure their appropriateness and therapeutic fit. Next, we will recruit and enroll 300 Black PWH who smoke to participate in a randomized controlled trial (RCT). Participants will be randomly assigned to: (1) MASP+; (2) the National Cancer Institute (NCI) QuitGuide smartphone app for standard mobile smoking cessation treatment; or (3) an assessment only control. Participants will complete a baseline assessment, daily ecological momentary assessments, and follow-up assessments at weeks 1, 2 (quit date for MASP+ and QuitGuide), 3, 4, 5, 6 (week 6 includes a qualitative interview for a subset of particip...