The last few decades has seen an increase in the application of the cognitive model with children. Central to the cognitive model is the concept that a distorted information processing system leads to cognitive distortions which in turn result in psychopathology. Within the child literature there are a range of self-report measures which aim to measure cognitive distortion in children. The psychometric properties of these measures have been shown to be dubious, and therefore, this study argues that a more psychometrically robust measure of cognitive distortion would have beneficial clinical implications. The study, therefore, examined the factor structure, reliability and concurrent validity of a newly designed measure of cognitive distortion for use with seven to eleven year old children. The study was conducted in three phases. Phase one involved the design of the measure; the Children's Inventory of Thinking Errors (CITE). During this phase items for inclusion in the measure were generated from children within the seven to eleven year age group. These items were generated through a semi-structured interview and through a review of clinical case notes. During phase two, the initial 20 item version of the CITE was administered to 154 seven to eleven year old children. Item analysis resulted in the elimination of three of the items from the CITE. Initial reliabilities were analysed, and a factor analysis resulted in the data being rotated on three factors. There was no coherent theoretical structure to these factors and therefore, the measure was scored as a unidimensional instrument. This was in support of predictions based on the literature that the CITE would measure one main construct of global cognitive distortion. Phase three tested the reliability and validity of the CITE. The 17 item version was administered to a further 103 seven to eleven year old children. A strong Cronbach's Alpha (.7515) provided sound internal-consistency reliability. Test-retest was provided for a six week interval and again this was psychometrically sound (.825). Factor analysis of this second wave of data supported the unidimensional findings of phase two. Concurrent validity was provided through measures of internalising psychopathology. The children, therefore, completed a measure of depression (the Mood and Feelings Questionnaire - Angold et al, 1987a; 1987b) and a measure of anxiety (the Revised Children's Manifest Anxiety Scale - Reynolds and Richmond, 1978). Concurrent validity was established through significant correlations between the total score on the CITE and both of these measures individually. Measures of parental report of externalising behaviours did not correlate significantly with the total score on the CITE. This was as predicted, and in support of the concept of a deficit model for externalising psychopathology. Through this study, the CITE was shown to be a valid measure of cognitive distortion in children. It also demonstrated that children between the ages of seven and eleven years of age can have a cognitively distorted thinking style. Supplementary findings, including gender interactions were discussed together with clinical implications and recommendations for future areas of research.