Mindful awareness (MA) and distress tolerance are emerging as robust predictors of mental health in populations with high levels of stress and trauma exposure, such as first responders. The combination of both protective factors may have potentiating benefits for mental health. First responders might especially benefit from high levels of MA if they are able to tolerate distressing present-moment experiences as needed. In this study, cross-sectional data were used to test whether distress intolerance (DI) moderated the relationship between MA and mental health. First responders (N = 176) completed an online assessment battery including measures of MA (Mindful Attention Awareness Scale), DI (Distress Intolerance Index), and mental health outcomes (i.e., Depression, Anxiety, and Stress Scale; Posttraumatic Stress Disorder [PTSD] Checklist for Diagnostic and Statistical Manual of Mental Disorders, 5th edition [DSM-5]; Secondary Traumatic Stress Scale; abbreviated Maslach Burnout Inventory; compassion satisfaction subscale of the Professional Quality of Life Scale; Satisfaction with Life Scale; and Brief Resilience Scale). Multiple regression models demonstrated that among first responders with higher DI, MA had a stronger association with lower anxiety and depression symptoms. Interactions between MA and DI were not significant for other outcome measures. However, higher MA and lower DI each independently predicted lower stress (lower posttraumatic stress, secondary traumatic stress, and general stress); higher MA independently predicted better occupational health (lower burnout and higher compassion satisfaction); and lower DI independently predicted positive mental health (greater resilience and life satisfaction). Results highlight the independent associations of high MA and low DI with first responders' mental health and underscore the importance of studying of interventions that promote both of these protective factors in first responders. (PsycInfo Database Record (c) 2022 APA, all rights reserved).