The diploma thesis deals with the matter of self-designed English language coursebooks in the environment of language schools. The research will be conducted by doing an interview with at least five Czech language schools (in person) and with one foreign language school, which uses a self-designed coursebook (this will be done via e-mail, provided the language school consents to fill in a questionnaire). The questions will be concerned with the schools' policy on their textbooks. The empirical part will include a comparison of one commercially published textbook (chosen based on the interviews with the Czech language schools) with a self-designed coursebook. The layout of the textbooks, topics, practical usage of the language, etc. will be considered and compared. The aim of the thesis is to discover whether self-designed coursebooks offer any benefits (or hide any disadvantages for that matter) compared to commercially published coursebooks. The chosen method is a case study as the number of the coursebooks compared is limited. There will be an interview done in person with chosen Czech language schools which use commercially published coursebooks and one written questionnaire done via e-mail with a foreign language school which uses a self-designed coursebook. The interviews and a questionnaire will provide a closer look into the matter of textbook usage and also the individual schools' policy on textbooks – why they have chosen a self-designed textbook, why not to choose one, how they have chosen their textbook, etc. Then, the most widely used commercially published coursebook among the Czech language schools will be compared with the one self-designed coursebook. The analysis/comparison will be focused on the layout, topics, how much practical usage is done, how much they deal with pronunciation, reading, listening, etc. The thesis will be used to deepen the author's knowledge about the matter of textbooks and in general, for future possible consideration about making a self-designed textbook, as its purpose is to discover whether this type of textbook offers any benefits.