To date, there has been limited research into mood responses among adolescents with intellectual disability. One reason for this is the absence of a reliable and valid measure for the assessment of mood among this population. The present study evaluated such a measure among a sample of 135 adolescents with mild intellectual disability. Results supported the factorial validity of a 12-item derivative of the Profile of Mood States, referred to as the Intellectual Disability Mood Scale (IDMS). Convergent and divergent validity was also supported. Overall, the IDMS showed encouraging psychometric characteristics as a measure of mood among adolescents with intellectual disability. It is hoped that the results of this study will stimulate further research to expand our knowledge of mood responses among this population.