Opera and theater creators, numerous teachers, and parents have recognized the value of music theater for children for some time now. However, this genre has not received much attention in research. This book provides a systematic introduction. It outlines the various forms of the genre as they have appeared throughout history (Latin school opera, fairy tale and magic operas, patriotic festivals, school and youth operas, staged plays, teaching pieces, children's operas, adaptations of repertoire operas, children's musicals). Most of these still exist in some form today. The most extensive section focuses on the works of composer Wilfried Hiller. The analysis of these 20th-century works aims to highlight what constitutes high-quality contemporary music theater for children.