A behavioral economic reinforcer pathology model theorizes that alcohol problems are influenced by steep delay discounting, overvaluation of alcohol reinforcement, and low reinforcement from alcohol-free activities. Extending this account to the comorbidity of alcohol problems and posttraumatic stress disorder (PTSD), the present study tested the hypothesis that alcohol problems and PTSD symptom severity would interact and be positively associated with indicators from these three domains. High-risk emerging adults from North America (Study 1, n = 1,311, Mage = 22.13) and general community adults from Canada (Study 2, n = 1,506, Mage = 36.80) completed measures of alcohol problems, PTSD symptoms, delay discounting, alcohol demand, and proportionate alcohol-related reinforcement. Across studies, regression analyses revealed significant main effects of alcohol problems and PTSD symptoms in relation to selected reinforcer pathology indicators, but no significant interactions were present for delay discounting or proportionate alcohol-related reinforcement. Interactions were observed for alcohol consumption at $0 (intensity) and the rate of change in consumption across the demand curve (elasticity; Study 1) and for elasticity and maximum alcohol expenditure (Omax; Study 2), but not in the predicted directions. Higher synergistic severity was associated with lower alcohol reinforcing value in each case. These findings reveal expected relations between reinforcer pathology indicators and both alcohol problems and PTSD symptomatology in general but did not support the hypothesized synergistic relationship. The relation between alcohol problems and PTSD is more complex than predicted by existing extensions of the reinforcer pathology model, warranting further investigation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).