Objective: The objective of this study was to investigate the predictive value of sex, age, body mass index (BMI), Eating Disorder Examination (EDE) score, social risk factors, and psychiatric comorbidities for hospitalization and hospitalization duration among children and adolescents suffering from eating disorders. Method: This prospective cohort study involved 522 consecutive patients who had been referred to a specialized eating disorder unit between January 1, 2009 and December 31, 2015; participants were followed up until August 1, 2016 by medical records. We used regression analyses to evaluate the prognostic value of sex, age, BMI, EDE, eating disorder diagnoses, social risk factors, and psychiatric comorbidities concerning inpatient hospitalization and hospitalization duration. Results: We found that younger age, higher EDE global score, lower BMI percentile, anorexia nervosa, a higher number of social risk factors, and the presence of diagnosed self-harm increased the odds of being hospitalized, while being female and having a comorbid autism spectrum condition increased the duration of hospitalization. No other psychiatric comorbidity was found to significantly predict hospitalization or duration of hospitalization. Discussion: The odds of being hospitalized were predicted by the severity of anorexia nervosa and indicators of social risk factors in the family, whereas the duration of hospitalization was predicted by having a comorbid autism spectrum condition, indicating a difference between the factors affecting the risk of hospitalization and the factors affecting the duration of hospitalization. This calls for further exploration of tailored treatments for eating disorders. Public Significance Statement: This study finds that hospitalization for an eating disorder is predicted by the severity of the illness, self-harm, and social risk factors. Duration of hospitalization is predicted by having a comorbid autism spectrum condition. These findings indicate that the treatment of eating disorders may require different treatment approaches depending on the presentation of the individual patient to reduce both the need for hospitalization and the length of inpatient stay.