It is assumed that group climate can have an effect on aggressive behavior in adolescents living in residential facilities, but it is largely unknown whether there are climate differences between the various types of residential institutions, and whether group climate differently affects aggression incidents among adolescents placed in institutions that differ in levels of security (and openness). In current research, the differences in perception of group climate between open, semi-secure, and secure residential youth care facilities were examined as well as the association between group climate and aggression. In total, 159 adolescents (96 males, 63 females) completed the Prison Group Climate Instrument (PGCI), and (aggressive) incidents were recorded during a period of 3 months. Perception of group climate—including support from staff, group atmosphere among adolescents, possibilities for growth, and repression—did not differ between the various types of residential care, except for possibilities for growth. Adolescents in open and semi-secure institutions experienced more possibilities for growth than their peers in secure institutions. A more positive perception of group climate in open institutions proved to be related to less aggressive incidents at the living group. For semi-secure and secure institutions, no relation between group climate and aggression was found. Also, the longer adolescents stayed in residential youth care, the more aggressive incidents occurred.