Social exclusion significantly reduces prosocial behavior, as demonstrated in seven experiments. Participants who felt socially excluded donated less money to a student fund, were less willing to volunteer for lab experiments, were less helpful after a mishap, and cooperated less in a mixed-motive game. These effects were consistent across different measures of prosocial behavior and were not influenced by self-esteem, mood, or trust. Instead, the reduction in prosocial behavior was mediated by a decrease in empathy, not by emotional distress or other factors. The study found that social exclusion leads to a temporary shutdown of the emotional system, reducing empathy and impairing the ability to understand and respond to others' needs. This lack of empathy undermines the capacity for prosocial behavior, as empathy is a key driver of such actions. The findings suggest that social exclusion can temporarily impair emotional responses, making individuals less likely to help or cooperate with others. The experiments used various manipulations of social exclusion, including feedback about a lonely future and peer rejection. The results showed that social exclusion led to significant decreases in prosocial behavior, regardless of the recipient of the help or the cost to the self. The effect was consistent across different contexts, including helping after a mishap, volunteering, and cooperating in a prisoner’s dilemma game. The study also found that empathy, particularly empathic concern, mediated the relationship between social exclusion and prosocial behavior. Participants who felt excluded showed less empathy toward others, which in turn reduced their willingness to help. These findings highlight the importance of empathy in prosocial behavior and suggest that social exclusion can have a profound impact on an individual's ability to engage in prosocial actions. The results have implications for understanding the psychological mechanisms underlying social exclusion and its effects on human behavior.Social exclusion significantly reduces prosocial behavior, as demonstrated in seven experiments. Participants who felt socially excluded donated less money to a student fund, were less willing to volunteer for lab experiments, were less helpful after a mishap, and cooperated less in a mixed-motive game. These effects were consistent across different measures of prosocial behavior and were not influenced by self-esteem, mood, or trust. Instead, the reduction in prosocial behavior was mediated by a decrease in empathy, not by emotional distress or other factors. The study found that social exclusion leads to a temporary shutdown of the emotional system, reducing empathy and impairing the ability to understand and respond to others' needs. This lack of empathy undermines the capacity for prosocial behavior, as empathy is a key driver of such actions. The findings suggest that social exclusion can temporarily impair emotional responses, making individuals less likely to help or cooperate with others. The experiments used various manipulations of social exclusion, including feedback about a lonely future and peer rejection. The results showed that social exclusion led to significant decreases in prosocial behavior, regardless of the recipient of the help or the cost to the self. The effect was consistent across different contexts, including helping after a mishap, volunteering, and cooperating in a prisoner’s dilemma game. The study also found that empathy, particularly empathic concern, mediated the relationship between social exclusion and prosocial behavior. Participants who felt excluded showed less empathy toward others, which in turn reduced their willingness to help. These findings highlight the importance of empathy in prosocial behavior and suggest that social exclusion can have a profound impact on an individual's ability to engage in prosocial actions. The results have implications for understanding the psychological mechanisms underlying social exclusion and its effects on human behavior.