Delay discounting is a basic behavioral process that has been found to predict addictive behaviors, and more recently, other mental health problems. Acceptance and Commitment Therapy (ACT), is a transdiagnostic treatment that appears to alter delay discounting, possibly through reducing psychological inflexibility. The current study sought to further bridge research on delay discounting and ACT by examining the relation of delay discounting to a broad range of selfreported mental health problems and measures of psychological inflexibility. A cross sectional online survey was conducted with 389 college students. Small negative correlations ranging between .09 and .15 were statistically significant between delay discounting and self-reported depression, anxiety, eating concerns, hostility, academic distress, and student functioning (only general social functioning and social anxiety were non-significant). Similar negative correlations were also found between delay discounting and measures of psychological inflexibility. Psychological inflexibility statistically mediated all of the relations between delay discounting and mental health problems such that delay discounting was no longer related to mental health problems when including the mediator. Overall, these results suggest that delay discounting is a transdiagnostic process relevant to a range of mental health problems, potentially through its impact on psychological inflexibility.