Purpose: This study describes the development and validation of the Group Climate Instrument for Children aged 8 to 15 years (GCIC 8-15), which purports to measure the quality of group climate in residential care. Methods: A confirmatory factor analysis was performed on data of 117 children in Dutch residential youth care. Reliability analysis was performed and concurrent validity was tested. Results: An adequate fit of a two-factor model indicated construct validity of the GCIC 8-15. Reliability coefficients were good, and a significant correlation between perceived group climate and treatment motivation supported concurrent validity. Discussion: The GCIC 8-15 can be used to identify positive and negative aspects of group climate in residential youth care and enables further group climate research with children.