Recent research into reason giving for depression has illustrated the importance of client beliefs about the cause of their depression. Reasons given have been found to be associated with level of depression, perceived credibility of treatments and therapy outcome. It has been suggested that giving reasons for depression is a form of rule-governed behaviour and as such can cause the depression to be harder to treat (i.e. the reasons become functionally true for the individual). This study investigates the reliability and validity of the Reasons for Depression Questionnaire (RFD; Addis, Truax, & Jacobson, 1995), a 48-item self-report measure developed to measure explanations for the causes of depression. The study provides preliminary normative data for both clinical (n = 123) and non-clinical (n = 105) UK samples. The data indicate high reliability for all subscales including a further subscale (biological) added since the measure was initially developed. Certain subscales correlate significantly with level of depression and specific aspects of self-esteem. This supports the validity of the measure and suggests that it is measuring a distinct concept rather than significantly overlapping with individuals' general beliefs about themselves.