Antisocial attitudes are among the strongest predictors of reoffending; however, there is little evidence to show that treatment-induced changes in antisocial attitudes correspond to changes in individuals’ risk of recidivism. This study examined relationships between within-treatment change in antisocial attitudes derived from the Measures of Criminal Attitudes and Associates (MCAA) and reoffending among a large sample of males convicted of violent offenses (N = 2,337). Residual change scores (RCS) and categories of clinically significant change (CSC) were used as indices of within-treatment change. A number of MCAA factor scores significantly predicted general and violent reoffending when assessed before and after treatment. RCS calculations of within-treatment change on the Violence and Antisocial Intent factors were also significantly associated with general reoffending outcomes. There was no evidence that within-treatment change on any measure had predictive validity for violent reoffending.