Abstract Posttraumatic stress disorder (PTSD) co-occurs frequently with hazardous alcohol outcomes, presenting considerable public health burdens and challenging traditional treatment approaches. Although accessible interventions able to adapt to individuals’ fluctuating internal risks within their natural environments are emerging, these just-in-time adaptive interventions have largely not yet considered the role of trauma sequalae in alcohol use. To do so, research needs to identify the acute risks for drinking operating in-the-moment as individuals experience PTSD symptoms in their daily lives. There is a critical need to define and operationalize acute cognitive processes underlying PTSD-related drinking (Aim 1), examine variability in such cognitions amid PTSD symptoms in real-world settings (Aim 2), and establish which of these acute cognitions are linked to actual drinking events and mediate PTSD-related drinking (Aim 3). During the K99 phase, Aim 1 comprises a fine-grained qualitative examination into acute risk cognitions among frequent drinkers with PTSD, utilizing focus groups to identify key acute cognitions and cognitive interviewing approaches to operationalize measures of such cognitions. Aim 2 field-tests these cognitive assessments by examining whether they vary across drinkers’ daily lives and are active amid PTSD symptoms within a 14-day ecological momentary assessment (EMA) study. During the R00 phase, Aim 3 considerably extends such work to test whether these acute cognitions are linked to actual drinking events as well as whether they are mechanisms of PTSD-related drinking across another 14-day EMA. Collectively, this mixed methods investigation will identify proximal cognitive mechanisms of PTSD-related drinking that can be targeted in future just-in-time interventions. As a K99/R00 NIH Pathway to Independence Award, these research efforts would support the emergence of a dedicated early career researcher (Dr. Zaso) with unique expertise in acute cognitive trauma-related drinking processes. This K99/R00 also would afford Dr. Zaso instrumental development in acute PTSD-related drinking processes, momentary assessment of affective alcohol cognitions, and the methodological/statistical techniques necessary to characterize momentary, real-world drinking processes. The mentorship team offers expertise in the intersection of trauma and alcohol use (Dr. Jennifer Read), with collaboration support on daily processes in PTSD-related drinking (Dr. Tracy Simpson), acute activation of alcohol cognitions (Dr. Robert Dvorak), optimization of mobile alcohol assessment and intervention (Dr. Tammy Chung), and statistical modeling of multilevel alcohol etiologies (Dr. Craig Colder). Dr. Zaso’s career development will occur within the Department of Psychology and Clinical and Research Institute on Addictions at the University at Buffalo, which comprise a rich intellectual environment with a network of productive addictions researchers. Overal...