This study investigated dysfunctional cognitions in Ten women diagnosed with bulimia nervosa. The cognitions were measured using different methodological approaches. Results obtained on the Bulimia Cognitive Distortions Scale (BCDS; a self-report questionnaire) were compared to data collected using a thought-listing procedure, which immediately followed a food consumption task. These women were assessed on these measures prior to, and on completion, of a twelve week Cognitive-Behavioural Treatment ( CBT) programme. Analyses of variance were utilised to compare both pre-treatment and post-treatment results on these measures, as well as the sensitivity of these measures. The results on both measures indicated that women with bulimia nervosa did demonstrate a number of maladaptive beliefs regarding control, eating, weight and food at the pre-treatment assessment. At the posttreatment assessment the women reported fewer maladaptive beliefs, increased efficacy for eating and less negative affect around food. A significant increase in adaptive coping strategies and adaptive beliefs were also evident following CBT. Changes in BCDS scores across treatment demonstrated a stronger association with changes in bulimic symptomatology than changes in verbalised maladaptive beliefs. This suggested the self-report questionnaire was a more sensitive measure of cognitive change, and that attitude change may be associated with a decrease in bulimic symptomatology. There was no significant difference between women who no longer met the diagnostic criteria and those who remained symptomatic on overall scores on the BCDS or on the verbalised beliefs category. These results are discussed in terms of the existing literature and the limitations of this study. It was concluded that further research is required to develop more sophisticated measures of cognitions and to understand the processes of CBT.