The prevalence of childhood obesity is increasing at an alarming rate and is implicated in the onset of serious and life threatening health problems of both a physical and psychological nature. The current research comprised of three main components. Firstly, the reliability of a readiness to change questionnaire was examined, which had been completed by parents of obese children enrolled in the Bodywise childhood obesity programme. Secondly, an analysis of outcome data from 36 families who completed the above programme was also undertaken in order to determine if the data identified their stage of change, as defined by the questionnaire Thirdly, four semi-structured interviews were conducted with families involved with the Bodywise programme. These parents provided information related to their experiences of lifestyle change, including what initiated change, what assisted change, and what barriers to change they had encountered. Findings revealed that in accordance with the transtheoretical model the readiness to change questionnaire was a reasonably reliable instrument for indentifying parents' readiness to change their child's eating patterns and physical activity levels. Analysis of the outcome data from the 36 families revealed individuals in the action stage of change for both eating and physical activity made more rapid change at the outset of the programme than individuals in earlier stages of change. In addition, information derived from the interviews with families identified several promoters and barriers to change, many of which were similar across families. Until now no studies have examined the application of the transtheoretical model to an intervention for childhood obesity. Previous research has shown support for the model's use with other health problems. Overall this study lends support for the utility of the transtheoretical model in childhood obesity intervention.