The goal of this study was to examine whether psychological dimensions of antisocial personality disorder (ASPD), as conceptualized by Kernberg (1992), could predict psychotherapy noncompletion (PNC) among 50 men found guilty of sexual abuse of children. All participants began a 65-week, court-mandated course of cognitive-behavioral psychotherapy, which 20 (40%) of them did not complete. Pretherapy personality was assessed with the Structured Clinical Interview for DSM Axis II Disorders (First, Spitzer, Gibbon, Williams, & Benjamin, 1997), the Personality Organization Diagnostic Form (Diguer, Normandin, & Hébert, 2001), and Blatt and colleagues' (Blatt, Bers, & Schaffer, 1993; Blatt, Chevron, Quinlan, Schaffer, & Wein, 1988) scales of mental representations, as well as the State-Trait Anger Expression Inventory (Spielberger, 1988). A discriminant function analysis, which explained 46% of the total variance, showed that descriptive (antisocial and narcissistic personality disorders), psychological (primitive defense mechanisms, identity diffusion and self-representations), and demographic (work status and income) variables predicted PNC. The classification analysis correctly classified 78% of the participants. These findings support the hypothesis that psychological dimensions of ASPD help explain PNC among sexual offenders. The authors discuss the theoretical and clinical implications of these results.