SUMMARY/ABSTRACT Among the disparities faced by populations in low- and middle-income countries (LMICs) are those related to tobacco use and secondhand smoke exposure (SHSe). Two countries particularly impacted by tobacco use and SHSe are Armenia (AM) and Georgia (GE), which represent the 11th and 6th highest smoking rates in men globally (51.5% and 55.5%, respectively). However, smoking prevalence is much lower among women (1.8% and 7.8%). Notably, a primary source of SHSe among children and most nonsmoking adults in many LMICs, including AM and GE, is the home. Smoke-free homes (SFHs) can reduce SHSe, promote cessation, and possibly disrupt initiation; however, 61.4% of households in AM and GE allow smoking in the home. Thus, promoting SFHs may be an innovative and relatively untapped strategy for chronic disease prevention in these countries – and in other LMICs with high smoking rates. Research focused on implementing evidence-based interventions (EBIs) offers unique opportunities to address the pressing needs in LMICs and to examine key barriers in the adoption, scale-up, and sustainment of EBIs in low-resource settings. This proposal builds on ongoing collaborations among MPIs Berg and Kegler, the GE National Center for Disease Control (NCDC), the AM National Institute of Health (NIH), and the American University of Armenia (AUA), dating back to 2013. These collaborations have established: 1) a strong community-based infrastructure for implementing public health programs using local coalitions in 14 communities, developed in our current Fogarty-funded R01; and 2) a theory-based SFHs intervention, designed to be brief and adaptable and shown to be effective, generalizable, scalable, and cost-effective among low-income households in the US. The current proposal will strategically capitalize on our strong partnerships with national public health agencies, local community mobilization infrastructure, and SFH EBI to address our specific aims. Aim 1: We will adapt our SFH intervention to be culturally appropriate for the AM and GE populations, using a community-engaged approach and robust adaptation frameworks and methods, and develop in-country capacity for intervention dissemination (via local coalitions) and delivery (via national quitlines). Aim 2: We will examine the effectiveness of the adapted intervention (vs. control) on SFH adoption (primary outcome) among households in AM and GE, using a type 1 hybrid effectiveness-implementation RCT (n=550 participants; 275/country), with follow-up assessments at 3 and 6 months. Aim 3: We will assess intervention reach, adoption, implementation, and maintenance potential, as well as related contextual influences, using a mixed-methods process evaluation guided by RE-AIM. Our team (including national public health agencies) will use these findings to develop a sustainability and dissemination plan (e.g., intervention packaging for scale-up). This work will provide a robust model for adapting and implem...