This chapter explores the cognitive and neural mechanisms underpinning our understanding of social interactions. It begins by examining social perception and attribution—how we interpret cues, form impressions, and assign causes to others’ behaviors—drawing on attribution theory and the roles of consensus, distinctiveness, and consistency. The chapter further explores theory of mind and empathy, which enables us to understand and share the mental and emotional states of others. It discusses the impact of stereotyping, prejudice, and discrimination on social judgments, as well as the dynamics of group behavior, collective cognition, and social influence. Nonverbal communication and social cues are highlighted as vital channels for conveying emotions and intentions. The text also covers how social identity and self-categorization shape intergroup relations and contribute to conflict and cohesion within groups. Additionally, cultural differences in cognitive styles and categorization are discussed, along with moral reasoning frameworks that guide ethical decision-making. Finally, the field of social cognitive neuroscience is introduced, showing how neuroimaging techniques reveal the brain regions involved in processing social information and addressing the ethical dimensions through neuroethics.