The aim of the diploma thesis is to provide a comprehensive picture of Czech and American cultures, not only in their interaction. This picture will be the basis for learning and understanding of both cultures and their mutual differences. A detection of cultural specificities, their clarification and explanation of their causes is a fundamental concern of this thesis. The main issue of the research is to uncover cultural differences and related cultural clashes. The second aim of the diploma thesis is building a list of potential cultural clashes and final recommendations for the Czechs to know how to prevent these conflicts.