This dissertation, "Children's Aggressive and Prosocial Behaviours: Exploring Age, Sex-related Differences, and the Role of Social Cognitive Functioning" by Ka-yee, Cavy, Lee, 李嘉怡, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Children's social behaviours have significant implications to their adjustments. Aggressive children display emotional, behavioural, and social problems. On the other hand, prosocial children are better adjusted (for review, see Card, Stucky, Sawalani, & Little, 2008). Adopting the social cognitive approach, the present study aimed to investigate the relationships between several social-cognitive capacities related to empathy (i.e., perspective-taking, affect sharing, and emotion regulation) and social behaviours (physical aggression, relational aggression, and prosocial behaviours) in children. The results showed that perspective-taking was the most predictive factor of both prosocial and aggressive behaviours, whereas the capacity to share emotions and to modulate emotion was found to have little predictive value to both positive and negative social behaviours. In addition, the present study also investigated the sex-related and age differences of aggressive behaviours in children. Consistent with the findings of previous studies, this study found that boys enacted more physical aggression than girls. However, sex-related difference in relational aggression was not found. Besides, older children were found to use more relational aggression but the trend of decreasing physical aggression across development was not evident. Clinical implications of the present findings were discussed. DOI: 10.5353/th_b4765710 Subjects: Aggressiveness in childrenInterpersonal relations in children