Child-to-parent aggression (CPA) constitutes a form of aggressive behavior that is the focus of increasing attention. Social information processing (SIP) models of aggression emphasize the role of the cognitive and emotional processes that occur when children address ambiguous social scenarios during the development of aggressive behavior. The present study develops a questionnaire to assess SIP when children cope with conflicts with parents and examines the bidirectional relations among several SIP components and CPA in a 1-year longitudinal study. A sample of 1,272 adolescents between 13 and 17 years of age completed measures of SIP and CPA in two waves, which were spaced 1 year apart. Confirmatory factor analyses provided support for a model with five correlated factors for the SIP questionnaire, as follows: hostile attribution, anger, aggressive response access, anticipation of positive consequences for oneself, and empathy. Longitudinal analyses indicated that hostile attribution in male adolescents and anger in female adolescents predicted an increase in CPA over time. In addition, initial levels of CPA predicted a worsening of several SIP components at the follow-up. The results were very similar for psychological and physical CPA. Bidirectional relations between CPA and SIP are discussed from the perspective of the social cognitive model of aggression.