Scholars have recently begun to explore the potential of educational media featuring counter-stereotypes in changing gender attitudes and beliefs, but so far experimental studies simulating interventions are lacking and preadolescents are understudied as target group. Further exploration of this research field is highly needed. In this mixed-design experimental study among 271 preadolescents (M[subscript age] = 10.34, SD = 0.77), we therefore examine the impact of watching and discussing an educational television program containing diverse and counter-stereotypical gender images in a classroom setting on preadolescents' gender attitudes and beliefs. Findings indicated that exposure to the program affects gender essentialism and acceptance of and willingness to affiliate with gender-nonconforming peers. However, after-exposure discussions in a classroom setting did not yield stronger results, nor did gender identity constructs moderate the effect. This study emphasizes the effectiveness of educational television in influencing components of gender attitudes and beliefs, but also suggests that a classroom setting may not be the most effective context for discussing such content with the goal of altering gender attitudes and beliefs.