This study compares 477 Chinese and 342 American adolescents’ responses to open-ended questions regarding attribution and outcome expectancies of relational aggression, and investigates how cultural values were related to these social cognitive processes. Results revealed cross-cultural similarities and differences. In particular, American adolescents attributed romantic relationship competition, which was absent in Chinese adolescents’ responses. Furthermore, American adolescents demonstrated a stronger instrumental orientation in their social cognition (e.g., gain status), whereas Chinese adolescents tended to hold the blaming the victim attribution, and the socially harm the victim outcome expectancy. Finally, this study revealed that in both cultural groups, higher collectivism was linked to the blaming the aggressor attribution, as well as escalated peer conflict and aggression as outcome expectancies, whereas individualism was linked to the blaming the victim attribution. Findings of this study enriched our knowledge about the cultural construal of adolescents’ attribution and outcome expectancy regarding relational aggression.