The objective of this research project was to construct a reliable and culturally relevant scale to measure aggressiveness in Mexican adults. A 96-item Likert scale was designed, on the basis of indicators drawn from a preliminary study and of theoretical formulations. Participants were volunteers from Mexico City. Five factors were obtained that group together 25 items explaining 61.59 % of the variance, α=0.92. In another study, a confirmatory factor analysis was performed, which showed adequate indexes of adjustment. Subsequently, correlations between personality and aggressiveness were obtained. Results show that the extroversion, affability, responsibility, and openness factors are negatively associated with aggressiveness, while neuroticism is positively associated. With respect to differences by sex, findings indicate that men show higher reactivity levels and women, higher frustration levels. e conclusion is that the scale is a valid and reliable instrument that makes it possible to identify differences among the five big personality traits, as well as between men and women.