Content protection for multimedia data is widely recognized especially for data types that are frequently distributed, sold or shared in digital and via Internet. Particularly, the music industry dealing with audio files realized the necessity for content protection. Distribution of music sheets will face the same problems. Digital watermarking techniques provide a certain level of protection for music sheets. Classical image-oriented watermarking algorithms for images suffer from several drawbacks when directly applied to image representations of music sheets. Therefore, new solutions have been developed which are designed regarding the content of the music sheets. In comparison to other media types, the development of watermarking algorithms for music scores is a rather young technology. The chapter reviews the evolution of the early approaches and describes the current state of the art in the field.