During adolescence, the identity formation process represents one of the main developmental tasks: adolescents use active behaviours of exploration. In particular, we assume that transgression (i.e. breaking rules and norms) can represents a sort of identity exploration, characterized by different types and functions with regard to the developmental phase. A narrative task was administered to 90 subjects of three different age-groups, attending high school (first and last grade) and university (second-year university students). This study was aimed at investigating the point of view of subjects with regard to the function, the structure and the meaning of transgression. We assessed the textual corpus at two levels of analysis: categorical content (by N-vivo software) and lexical content (by T.lab software). The results showed that the transgressive behaviours played an exploratory and developmental function and that there are some age groupsrelated differences.