The authors investigated the effects of mock juror age (younger vs. older), defendant age (22 vs. 65), and type of excuse defense used by defendants (a highly self-inflicted condition, Cocaine Dependency Disorder, vs. a less self-inflicted condition, Posttraumatic Stress Disorder) on mock juror decisions. Ninety-six younger and 96 older adults read a scenario and answered a questionnaire. Results indicated that the defendant using the highly self-inflicted excuse was more likely to receive a guilty verdict and a longer sentence than was the defendant using the less self-inflicted excuse. Older jurors were more certain of their verdicts and saw the defendant as more responsible for his condition than did younger jurors. Defendant age did not affect juror decisions. In addition, excuse type and juror age affected the jurors' perceptions of the victim's responsibility for the attack. The authors discuss the potential influence of juror age on perceptions of defendant responsibility.