Gender Mainstreaming is a new strategie of equal treatment of men and women. Due to this concept, still existing social and structual sex differences and distinctions between men and women should be stopped and removed. In this thesis, the legal historical development of this concept is demonstrated, beginning in the 1960s with the development cooperation of the United Nations with the southers countries like Aftica and Latin America, up to the Worldwomen`s Conferences, where the concept of Gender Mainstreaming had ist`s break through in Beijing in the year 1995. Following up, the Gender Mainstreaming concept found it`s way into the European Union. With the Contract of Amsterdam,whitch came into effect 1999, the concept was legally binding for the first time. The adjudications of the European Court in connection with the system of quotas are also considered. The last part of the thesis is about the Gender Mainstreaming concept in Austria and how it is implemented in the Austrian law. As an example for the equal treatment of men and women, the law for the equal treatment of men and women from 1979 and 1993 are named.