*OURNAL฀OF฀#HILDRENS฀3ERVICES฀฀s฀฀6OLUME฀฀)SSUE฀฀฀s฀฀/CTOBER฀฀･฀0IER฀0ROFESSIONAL฀,TD 36 Abstract The Dutch juvenile justice system locks up an increasing number of adolescent boys and girls at a cost of approximately 250,000 for each inmate annually (Boone & Moerings, 2007; Tonry, 2005). Questions have been raised, however, about the cost-effectiveness of treatment in closed institutions. This study, with a sample of 49 adolescents residing in a Dutch youth prison, examined the role of group climate in establishing and maintaining treatment effects. Results show that an open group climate, with group workers paying more attention to the psychological needs of the adolescents and giving them ‘space’ to experiment, led to inmates feeling that they were ‘being understood by the group workers’. This perception of being understood was associated with greater treatment motivation and higher internal locus of control. Positive prison workers in the living group turned out to be a key factor in building an open group climate and subsequently higher internal locus of control and greater treatment motivation. Key words youth crime; juvenile delinquency; group climate; youth prison been raised concerning the negative effects of incarceration and coercion (Garrido & Morales, 2007; Parhar et al, 2008). Next to adequacy Introduction In recent systematic reviews of the effectiveness of correctional treatment in reducing recidivism among juvenile delinquents questions have ‘What works’ for juvenile prisoners: the role of group climate in a youth prison Peer van der Helm (MSc) is research director at Leiden Professional University (School of Social Studies), The Netherlands Marian Klapwijk (BA) is group worker in a youth prison in Holland, The Netherlands Geert-Jan Stams (PhD) is associate professor at the University of Amsterdam (Department of Forensic Child and Youth Care Studies), The Netherlands Peter van der Laan (PhD) is professor occupying an endowed chair at the University of Amsterdam and the Free University of Amsterdam, and senior researcher of the NSCR (National Institute of Crime Research), The Netherlands