The Children’s Sleep Comic is a standardized self-report questionnaire for assessing insomnia in children ages 5–11 years. The goal of the present study is to introduce a revised version of this measure and to present psychometrics and a cut-off score. Therefore, the revised Children’s Sleep Comic, the Sleep Self Report, the Children’s Sleep Habits Questionnaire, and the Child Behavior Checklist were applied to a sample of 393 children and their parents. Of the parents who participated voluntarily, a subsample (n = 176) was interviewed on the phone to diagnose their children with sleep disorders according to the International Classification of Sleep Disorders, if applicable. The results indicated that the Children’s Sleep Comic is a reliable self-rating instrument for diagnosing childhood insomnia. Internal consistency was α = 0.83; and convergent and divergent validity were adequate. The child-friendly format can foster a good therapeutic relationship, and thus establish the basis for successful intervention.