Emotional contagion is the tendency to express and feel emotions that are similar to and influenced by those of others. Emotional contagion may be involved in crowd behaviors, like collective fear, rage, or moral panic, but also emotional interactions in smaller groups such as negotiation, teaching and persuasion contexts. It is also the phenomenon when a person (especially a child) appears distressed because another person is distressed, or happy because they are happy.

To date, most clinical research has focused on the effects on non-verbal (and often non-emotional) displays, and relatively less has been studied about the impact of contagion effects on emotional feelings. Emotional contagion and empathy may be related, but the nature of such a connection has not to date been explored either.

The concept of insulating oneself from emotional contagion is called emotional detachment.