Affect tolerance/sensitivity, broadly defined as the ability to withstand negative emotional states, has been implicated in the development and maintenance of numerous forms of psychopathology, negative health behaviors, and chronic illnesses. Though considered a trait-like predisposition, affect tolerance/sensitivity factors are malleable and have been posited to improve with mindfulness and acceptance interventions. The aim of the current review was to synthesize the available literature evaluating mindfulness and acceptance interventions on affect tolerance/ sensitivity. Results: Seventeen randomized controlled trials with 16 unique samples (pooled N=1001) were included. Interventions ranged from 15 min to 12 weeks. Studies included outcomes of anxiety sensitivity (fear of arousalrelated sensations; n=8), distress tolerance (ability to withstand emotional distress; n=6), and intolerance of uncertainty (inability to withstand uncertain states; n=3). Most studies included healthy adults (25%), those with an anxiety disorder (25%), or substance use problems (19%). Mindfulness and acceptance interventions were associated with greater longitudinal improvements in affect tolerance/ sensitivity compared to inactive controls (n=7), similar improvements compared to active interventions (eg, cognitive behavioral therapy; n=7), and greater short-term improvements compared to acute experimental conditions (eg, avoidance, rumination; n=3). Studies were generally of moderate quality. Further formal meta-analysis is forthcoming. Conclusions: Mindfulness and acceptance interventions appear promising for improving affect tolerance/sensitivity across multiple populations. Future work is needed to determine whether specific mindfulness or acceptance interventions differentially improve affect tolerance/sensitivity and whether these improvements mediate treatment outcomes.