Purpose-We tested the hypothesis that, at two different stages of adolescence, impairment in emotional well-being associated with obesity is mediated by body dissatisfaction.Methods-Self-report measures of body dissatisfaction, emotional well-being (self-esteem, depressive mood), height and weight and socio-demographic information were completed by the same female (n=366) and male (n=440) participants during early (mean age = 12.8 years) and late (17.3 years) adolescence. For each measure and at each time point, the hypothesis of mediation was tested using the methods suggested by Baron & Kenny (1986).Results-The conditions of complete mediation were satisfied in all 6 cases for which an effect of obesity on emotional well-being was observed. That is, in each of these cases, obesity was no longer associated with lower self-esteem or with higher depressive mood after the effects of body dissatisfaction were statistically controlled. Among females, there was no association between obesity and depressive mood at either time point.Conclusions-Impairment in the emotional well-being of overweight adolescents, where this is observed, may be due primarily to the effects of weight-related body dissatisfaction. This appears to be the case for both boys and girls and during both early and late adolescence. The findings are consistent with the view that body dissatisfaction is central to the health and well-being of children and adolescents who are overweight and that distress associated with negative body image may warrant greater attention in the context of obesity prevention and treatment programs. Keywords obesity; body dissatisfaction; emotional well-being; mediation Emotional well-being is a particularly important component of overall health and well-being during childhood and adolescence, in that the chronic medical conditions that often affect physical health in adulthood are comparatively uncommon earlier in life [1]. That being the case, and given the marked increases in the prevalence of obesity observed in many countries in recent years, weight-related impairment in the emotional well-being of children and adolescents has come to assume greater significance in obesity research [2,3].Population-based studies of the association between obesity and emotional well-being have, however, yielded inconsistent findings in both children and adolescents and adults [4,5]. Whereas obesity has been found to be associated with low self-esteem, depressive mood, and similar forms of impairment in some studies [2,6,7], in other studies no association has been observed [3,8,9]. As a consequence, attention has turned to variables that might mediate the association between obesity and emotional well-being; that is, variables that might account for the fact that emotional well-being is impaired in some obese individuals but not others [4,5].One variable that appears to be worthy of further investigation in this regard is body dissatisfaction (BD), a construct that may be defined as a person's subjective dissatisfaction with h...