We addressed explanations for why prisoners manifest the Better‐Than‐Average Effect (perceptions of superiority to the average peer), focusing on three biases: self‐enhancing (social as well as temporal) comparisons, denial, and self‐serving attributions. We tested the Better‐Than‐Average Effect in regards to prisoners’ perceptions of their worst trait, and assessed the relationship between the three biases and positive self‐evaluations. Prisoners engaged in self‐enhancing comparisons, differentiating themselves from other prisoners and their past selves who committed the crime, but also expected self‐improvement in the future. Prisoners also demonstrated denial for intentions to commit the crime, planning of it, recidivism, and over‐estimation of crime prevalence in the general population. Although prisoners made self‐serving attributions by distancing their own character from their criminal behavior and reporting they had experienced more hardship relative to others, they did not attribute the cause of their crime to such hardship. More extensive self‐enhancing temporal comparisons and denial predicted more positive self‐evaluations of prisoners’ worst trait relative to the average community member. The strength of some of these biases varied with levels of narcissism and psychopathy.