Self-reports on domestic violence inventories remain the basis of court and clinical decision-making and program outcome evaluations, but previous research questions their reliability and validity. Accurate prediction of underreporting would help practitioners and researchers adjust batterer and victim self-reports. We develop prediction equations of underreporting on the Conflict Tactics Scale, using a multi-site database of men admitted to batterer programs and their female partners (n = 840). First we use variables measured at program intake to predict female and male underreporting of male violence at program intake. Second, we use variables measured at program intake, as well as measures of program participation, to predict male-female disagreement (male underreporting) at 12-month follow-up. Several variables were predictive of underreporting, both at intake and follow-up, but overall prediction was marginally better than chance. The findings suggest that men and women underreport based on situational factors (such as relationship characteristics) and rational reasons, rather than based on personality traits or social desirability. However, the ability to predict underreporting is too weak for adjustment of self-reports by clinicians and program evaluators.