Objective: Mental contamination is a term used to describe a psychological state in which one feels a sense of contamination or dirtiness in response to cognitive processes such as intrusive thoughts or memories. This gives rise to negative emotions and an urge to wash. Research has begun to identify predictors that might explain individual differences in sensitivity to feelings of mental contamination. The current study aimed to add to this evidence base, exploring perfectionism, tendency to the cognitive bias moral thought-action fusion and shame-proneness as possible predictors. Design: An online survey was designed to assess whether individual differences in these factors were associated with sensitivity to mental contamination. The survey measured the above variables, and included an induction task which asked participants to recall a time they committed a moral transgression toward another person. Feelings of mental contamination (anxiety, sense of internal and external dirtiness and urge to wash) were measured before and after the induction, with changes indicative of sensitivity to mental contamination. Participants: Participants (N = 131; 71.8% female) were recruited from the general public via social media advertisement and snowball sampling. Results: Shame-proneness and subscales of perfectionism (high standards and discrepancy) were found to correlate positively with indices of mental contamination (anxiety and feelings of internal and external dirtiness). Shame-proneness emerged as a significant predictor of these indices. Furthermore, the relationship between shame-proneness and mental contamination indices was found to be moderated by duration spent thinking about the moral transgression. Conclusions: Results of this study point to the potential importance of targeting shame-proneness and rumination in the treatment of mental contamination based difficulties. Participants varied in their response to the induction procedure which may point to the importance of idiosyncratic induction procedures in future research.