StartingpointTextbooks are a very important type of book for every kind of science. They include, per definitionem, the current state of a discipline and give a systematic overview of the field. A first look into different textbooks (both German textbooks of Didaktik and English textbooks of Instructional Design) shows that there are many differences between them. These differences are the result of the work of an author, especially of checking knowledge and selecting contents. The work of authors has not been the subject of much research from this point of view. In this case a look at the history of education can be helpful. In the 18th century you will find the textbook "Grundsätze der Erziehung und des Unterrichts" (Principles of Education and Teaching) of August Hermann Niemeyer, the most important didactic textbook of that period. The reasons for Niemeyer's success are to be found above all in the method he applied: "Check it all! Keep the best!" (a sentence out of the bible) was his motto and belonging to no system his declared conviction. He described himself as an eclectic. And nowadays eclecticism also seems to be an important method in writing a textbook. In modern theories this eclectic idea has been taken up and developed in more detail. Research questions1. Which understanding of Didaktik / Instructional Design is disclosed in German and English textbooks?2. How do authors arrive at the contents of their textbooks of Didaktik / Instructional Design?3. Is it possible to create from this a guide for writing a textbook? Objects of research are current textbooks of Didaktik and Instructional DesignKron, Friedrich W.: Grundwissen Didaktik, 4th edn, 2004 Glöckel, Hans: Vom Unterricht, 4th edn. 2003 Peterßen, Wilhelm H.: Lehrbuch Allgemeine Didaktik, 6th edn., 2001 Gagné, Robert M.: Principles of Instructional Design, 5th edn., 2004 Smith, Patricia: Instructional Design, 3rd edn., 2005 Dick, Walter: The Systematic Design of Instruction, 6th edn., 2004 FrameworkWith the help of the theoretical foundations which I describe below, the textbooks of Didaktik and Instructional Design just quoted will be surveyed. Starting from the motto "Check it all! Keep the best!" there are four subquestions for research1. Which fields of knowledge are mentioned in a textbook of Didaktik and Instructional Design for the finding of contents? Aim of the research is to define the field of knowledge in which the Didaktik / Instructional Design stands. To answer this question I undertake a content analysis which focusses on the references and argumentation.2. How are the contents of these fields of knowledge described and with the help of which criteria are they checked?Aim of the research is to define pedagogical strategies for selection of knowledge and contents. To answer this question I undertake a content analysis which focusses on the argumentation of an author. 3. Which contents are mentioned in a textbook of Didaktik and Instructional Design? What are the contents which are most important for didactics as a science? Aim of the research is to define the differences and correspondences in the field of Didaktik and Instructional Design. To answer this question I undertake a content analysis which focusses on the argumentation and the table of contents of the textbooks of Didaktik / Instructional Design.4. What is the systematic basis of the textbooks of Didaktik / Instructional Design in regard to content? Aim of the research is to define a pedagogical and scientific systematics of Didaktik and Instructional Design. To answer this question I undertake a content analysis.Theoretical foundationsBasically there are two theoretical linesOn the one hand theories of eclecticism are important. In the pedagogical field I mention among others August Hermann Niemeyer, Wolfgang Klafki und Lothar Wigger. In the philosophical field I mention first of all Ken Wilber. His philosophy pursues an integral approach and thus contains clear elements of a positively understood eclecticism. On the other hand theories on the writing of textbooks are important. In first place I mention Bernard Bolzano, who has written the most recent complete theory on writing a textbook. Both theoretical lines must be taken up and linked under the motto "Check it all! Keep the best". Methodical procedureTo answer the subquestions I use content analyses which focus on the references, the argumentation of an author or the table of contents. And in view of the shifts between the theoretical and the practical levels the overall methodical approach is hermeneutic. 1. Conclusions about the self-understanding of Didaktik / Instructional Design. 2. Conclusions about the writing of a textbook of Didaktik / Instructional Design. 3. Encouragement of international exchange between German Didaktik and English Instructional Design.4. A guide for writing a textbook of Didaktik / Instructional Design. Albrecht, Michael: Eklektik, 1994 Bolzano, Bernard: Wissenschaftslehre, vols. 1 - 4, Leipzig: Weiner, 1931 Dick, Walter O. / Carey, Lou / Carey, James O.: The Systematic Design of Instruction, 6th edn., 2004 Früh, Werner: Inhaltsanalyse, 2004 Gagné, Robert M. / Golas, Katharine / Keller, John M.: Principles of Instructional Design, 5th edn., 2004 Kron, Friedrich W.: Grundwissen Didaktik, 4th edn., 2004 Landsheere, Gilbert de: August Hermann Niemeyer, in: PROSPECTS, 1999 Niemeyer, August Hermann: Grundsätze der Erziehung und des Unterrichts, 9th edn., 1832 Peterßen, Wilhelm H.: Lehrbuch Allgemeine Didaktik, 6th edn., 2001 Seel, Norbert M.: Instruktionsdesign: Modelle und Anwendungsgebiete, in: Unterrichtswissenschaft, 1999 Smith, Patricia L. / Ragan, Tillmann J.: Instructional Design, 3rd edn., 2005 Wilber, Ken: The eye of spirit - An integral vision for a world gone slightly mad, 2001 Zierer, Klaus: Das Verschwinden eines Klassikers, in: Vierteljahrsschrift für wissenschaftliche Pädagogik, 2005 , monograph