Although impairments in mentalizing and dissociation have been linked to the onset of eating disorders, there is still a paucity of studies investigating their relationships among adolescents. This study aimed at investigating the role of failures in reflective functioning and dissociation in predicting the risk of eating disorders during adolescence. The Eating Disorder Inventory-3 (EDI-3), the Reflective Functioning Questionnaire (RFQ), and the Adolescent Dissociative Experiences Scale (A-DES) were administered to a sample of 427 adolescents between 13 and 20 years old. Results of correlational analysis showed that the risk of eating disorders was positively correlated with uncertainty about mental states. Eating disorder risk was also inversely correlated with certainty about mental states. Dissociation scores and its domain scores were all positively related to the risk of eating disorders. Results of regression analysis displayed that uncertainty about mental states and dissociation were statistically significant predictors of an increased risk of eating disorders. Gender and BMI were also significant predictors in the final model, which explained 24% of the variance. Regarding the specific dissociative domains, findings indicate that the depersonalization/derealization factor was the only significant predictor for the risk of eating disorder. The present study points out that uncertainty about mental states and dissociation could play a relevant role in increasing the risk of eating disorders during adolescence.