Background: Emotion dysregulation (ED) is a transdiagnostic variable that accounts for the onset and mainte-nance of mental health disorders. The interplay between ED, cannabis use and mental health has not been appraised in the young adult population and whether there are sex-dependent effects has yet to be examined. This study looked at whether ED mediates the association between past-month cannabis use and mental health, while considering sex as a moderator.Methods: 2,762 (64.2% women) undergraduate Spanish students completed an online battery. Among others, they fulfilled the Depression Anxiety Stress Scale-21 (DASS-21) and the Difficulties in Emotion Regulation Scale (DERS-28). A two-way ANOVA assessed the effects of sex and past-month cannabis use on participants' DASS-21 scores. A set of moderated mediations tested whether the indirect effect of past-month cannabis use on DASS-21 through DERS differed by sex.Results: Past-month cannabis female users showed higher levels of depression, anxiety and stress (M = 51.10, SD = 26.72) than did men [(M = 33.76, SD = 20.31); F(1, 2758) = 5.119, p =.024, eta 2p =.002]. In female young adults only, the effect of past-month cannabis use on mental health was mediated by ED (total score), non-acceptance of emotional responses, lack of emotional control, difficulties in engaging in goal-directed behavior, and lack of emotional clarity (all p's < 0.005)Conclusions: Findings indicate the importance of considering ED in assessment and intervention practices. In-terventions targeting ED may be particularly effective for female young adult cannabis users.