This bibliographic research is part of an effort to understand High School education in our country through the analysis of the National Guidelines and Curricular Parameters, with theoretical support from the discussions raised by the consulted bibliography, highlighting especially Décio Gatti Junior, Itamar Freitas, and Maria Inês Sucupira Stamatto. The expansion of this segment of education throughout Brazil shows the need to understand the nature and the various changes it underwent during the 19th and 20th centuries, as well as the role of the history discipline and its current configuration in the Guidelines and Curricular Parameters. It is observed, through research in articles and other academic texts, that High School education has had different conceptions, ranging from preparation for university courses to technical vocational training for the job market, and this ambiguity permeates the legislation relevant to it. So, this article intends to bring some statements about High School in a changing world.