My research program is located at the crossroads of justice, morality, and aggression. First, I'm interested in what people hope to gain when they take revenge, when they opt for a particular kind of penalty for criminal offenses, and what they regard a "fair" retribution. Second, I'm trying to find evidence for the notion that people who have high moral standards and a strong moral identity behave immorally every now and then. A trait variable that may help disentangling this paradox is "justice sensitivity." Third, I'm interested in the effectiveness of social competence trainings to prevent or reduce aggression and violence among children and adolescents. Fourth, I'm interested in research methods, especially in new methods for the analysis of change.