The current thesis firstly investigated the effectiveness of the IRAP as an accurate measurement of private verbal behaviours related to body weight/image dissatisfaction. Secondly, it implemented an applied study using a component from ACT and CBT in conjunction with experimental procedures to measure the believability and discomfort of target behaviours related to body image dissatisfaction and self/body-esteem. A series of pilot studies enhanced the practical application of experimental procedures and provided the textual stimuli for Experiment 1. The first experiment compared the IAT and the IRAP along with a series of explicit measures to investigate the measurement of weight related attitudes and self-esteem. These results demonstrated the IRAPs potential to measure relational responses related to the target behaviours. Experiment 2 investigated the utility of an Ideal and Perceived Body Image IRAP's as suitable measures of implicit attitudes towards target behaviours. In this experiment the Body Image IRAPs out-performed the textual IRAP employed in Experiment 1. The final study measured the effect of cognitive defusion and cognitive distraction on the frequency, the discomfort and believability of target thoughts. Specifically in relation to the effect acceptance of negative thoughts had on decreasing the believability or discomfort of negative cognitions. These findings indicated advantages for using cognitive defusion over cognitive distraction.