Rule-following us a variable that has been related to other factors relevant to the study of driver aggression. This study aims to create and validate an inventory that is able to evaluate said variable in the city of Cuernavaca, Morelos (Mexico). Using a two-phase methodology, this study produces a 10-item Likert scale that satisfies optimal levels of adjustment, which implies that it is valid for use in said city. These two phases satisfy requirements for content validation and construct validation. The Rule-Following Inventory will be of use for research in Traffic Psychology, allowing future research to be carried out.