We developed a new measure designed to facilitate research on the potential role of men's attitude toward sexual aggression against women in gender-based sexual violence: the Attitude toward Sexual Aggression against Women (ASAW) scale. We created a large pool of items, in which participants were asked to evaluate how bad it would be if they engaged in various sexually aggressive behaviors in a variety of scenarios. Three independent samples of men recruited from online panels (N = 380, 149, and 322) completed these items. Based on their responses, we retained 13 non-redundant items that had the most variance and covered a wide range of sexually aggressive behaviors (e.g., unwanted sexual touching; non-consensual sex), tactics (e.g., threatening to damage her reputation; using physical force), and contexts (e.g., the woman previously agreed to some sexual activity; the woman is intoxicated). An exploratory factor analysis found that all 13 ASAW items loaded strongly onto one factor, which suggests a unidimensional structure. If future research finds evidence for the construct validity of its scores, potential uses for the ASAW include risk assessment, treatment-related attitude-change, and research into the potential causal role of attitudes in sexual aggression against women.