I investigate group processes, especially the antecedents and aftermath of ostracism (being excluded and ignored). In my first line of research, I study the extent of ostracism’s aftermath on social pain, psychological needs, affect, and aggression. I also investigate whether individual differences and situational factors moderate ostracism’s immediate and delayed effects. In my second line of research, I investigate the antecedents to ostracism. Why are individuals ostracized? Using several manipulations, I found individuals are likely to be ostracized if they are perceived as burdensome to the group. In both lines of research, I extend my work to include intergroup relations, non-verbal communication, and individual differences.