Background: There is increased interest in developing training in cognitive behaviour therapy (CBT) with children and young people. However, the assessment of clinical competence has relied upon the use of measures such as the Cognitive Therapy Scale-Revised (CTS-R: Blackburn et al., 2001) which has been validated to assess competence with adults. The appropriateness of this measure to assess competence when working with children and young people has been questioned. Aim: This paper describes the development and initial evaluation of the Cognitive Behaviour Therapy Scale for Children and Young People (CBTS-CYP) developed specifically to assess competence in CBT with children and young people. Method: A cross section of child CBT practitioners (n = 61) were consulted to establish face validity. Internal reliability, convergent validity and discriminative ability were assessed in two studies. In the first, 12 assessors independently rated a single video using both the Cognitive Behaviour Therapy Scale for Children and Young People (CBTS-CYP) and Cognitive Therapy Scale-Revised (CTS-Revised: Blackburn et al., 2001). In the second, 48 different recordings of CBT undertaken with children and young people were rated on both the CBTS-CYP and CTS-R. Results: Face validity and internal reliability of the CBTS-CYP were high, and convergent validity with the CTS-R was good. The CBTS-CYP compared well with the CTS-R in discriminative ability. Conclusion: The CBTS-CYP provides an appropriate way of assessing competence in using CBT with children and young people. Further work is required to assess robustness with younger children and the impact of group training in reducing inter-rater variations.