This study's primary aim was to evaluate factors that influence attitudes toward the insanity defense in a sample of 578 college undergraduates. In addition to a comprehensive demographics survey, participants completed the Insanity Defense Attitude Scale-Revised (IDAS-R) and the Attitude Toward the Death Penalty (ATDP) Scale. Favorable attitude toward capital punishment and misperceptions about overuse of the insanity defense were related to negative attitudes toward the insanity defense. Hierarchical regression analyses demonstrated that possessing a favorable attitude toward capital punishment was the most robust predictor of a negative attitude toward the insanity defense. These findings provide valuable information about factors that create and maintain biases against the insanity defense and suggest areas of inquiry that could aid attorneys in selecting unbiased jurors.