»Foundation and Limits of Criminal Participation through Omission«: This doctoral thesis deals with the question of participation through omission. When the guarantor has an obligation to prevent or obstruct the commission of another person, but he violates that obligation, is he a »principal« or only a »secondary party« of this commission? The author uses a method which combines legal philosophy, norm theory, and doctrinal theory of criminal law to analyse the existing views comprehensively and develops a differential solution to the controversial question.