Self‐categorization theory (SCT) explains the situations in which people perceive themselves as either individuals or group entities. Instead of studying individuals as isolated from social experience, SCT proposes that it is important to understand the psychological nature of the self (e.g., mind, memory, cognition, behavior) within the scope of social groups and membership. In this entry, a number of key concepts of SCT are discussed, including levels of self‐categorization, stereotyping and self‐stereotyping, social influence, and salience of social categories. Current media psychology research within the domain of SCT is also reviewed.