The aim of this study was to elaborate a questionnaire to assess social information processing (SIP) related to aggressive behavior in adolescents. This questionnaire consists of five situations that adolescents have to imagine to assess the following SIP components: Interpretation, Anger, Response selection, and Emotion regulation. Confirmatory factor analyses supported the structure of the questionnaire in a sample of 1231 adolescents aged between 12 and 17. Furthermore, an alternative version of the questionnaire was developed with Likert response items. This version showed good structure and internal consistency (between .66 and .87). SIP components were differently associated with proactive and reactive aggression. Finally, boys scored higher than girls on SIP components characteristics of aggressive behavior.