Body Image is a major factor affecting health in a range of age groups, but has particular significance for adolescents. The aim of this research is to evaluate the efficacy of the Girls on the Go program delivered outside of the school environment by health professionals to girls at risk of developing poor self-esteem on the outcomes of self-esteem, impairment induced by eating disorders, body satisfaction, self-efficacy, and dieting behaviour. Method: A stepped wedge, cluster randomised controlled trial that was conducted in two phases on the basis of student population (Study 1 = secondary school age participants; Study 2 = primary school age participants). The waiting list for the Girls on the Go program was used to generate the control periods. A total of 12 schools that requested the program were separated into study 1 or 2 on the basis of student population (Study 1 = secondary, Study 2 = primary). Schools were matched on the basis of number of students and were allocated to receiving the intervention immediately or having a waiting list period. Study 1 had one waiting list period of one school term, creating two steps in the stepped-wedge design (i.e. 3 schools were provided with Girls on the Go each term over 2 terms). Study 2 had two waiting list periods of one and two school terms, creating three steps in the stepped-wedge design (i.e. 2 schools were provided with Girls on the Go each term over 3 terms). Primary outcome measures were self-esteem and impairment inducted by eating disorders. Discussion: There is a lack of preventative interventions currently available that address low self-esteem, low self-efficacy and body dissatisfaction in young women.