ENThe aim of this study was to test the moderating role of sport participation in the mediation model of media pressures, internalisation of appearance ideals and body dissatisfaction in adolescent boys. Five hundred and seventy adolescent boys (mean age 17.2 ± 0.45; range 15–19 years) participated in the cross-sectional study. Adolescents completed a questionnaire consisting of measures of attitudes towards sociocultural pressures on appearance, body dissatisfaction and sport participation (participation in achievement sport, leisure exercising and non-participation in any sports). Sports participation moderated the associations between the internalisation of stereotyped appearance ideals and body dissatisfaction. In athletes, the effect of internalisation of thin body ideals on body dissatisfaction was not significant, while the effect of internalisation of muscular/athletic body ideals was negative. In leisure exercisers, the effect of internalisation of muscular body ideals on body dissatisfaction was not significant, yet internalisation of thin body ideals had a significant effect on body dissatisfaction. The strongest associations between appearance ideals internalisation and body dissatisfaction were found in adolescent boys who reported no participation in sports. Sports participation might be an effective tool in decreasing the negative effect of internalisation of stereotyped appearance ideals on adolescent boys’ body image. Keywords: Media pressures; internalisation; negative body image; adolescent boys; sports and physical activity. [From the publication]