Objective: To examine associations between menstrual cycle phase, negative mood, sexual risk recognition deficits (assessed via an analogue risk vignette), and in vivo emotion dysregulation. Participants: Participants were 714 college women recruited between February 2007 and December 2009. Methods: Participants were randomly assigned to a negative or neutral mood induction and instructed to identify sexual risk during an audiotaped sexual coercion vignette. Participants reported menstrual cycle information, in vivo emotional nonacceptance, and attention during the vignette. Results: In the negative mood condition, ovulation was associated with longer risk recognition latencies relative to the luteal and follicular phases of the menstrual cycle. Increased in vivo emotional nonacceptance and decreased attention to the vignette mediated associations between ovulation and risk recognition deficits in the negative mood condition. Conclusions: Sexual assault risk reduction programs could provide psychoeducation regarding negative mood during ovulation and emphasize emotional acceptance and attention to external stimuli when distressed. (Contains 3 tables.)