This thesis deals with the topic of same-sex marriage and homosexuality. It describes how the two phenomena were accepted throughout centuries with attention primarily drawn to the United States, which is, however, for better illustration, compared with other countries. The work offers various points of view such as religious, medical, and political, all of which affected the position of both same-sex marriage and homosexuality. The aim of this thesis is to provide arguments which condemned same-sex marriage in the past as well as those which were in favor of it, and, thanks to its structure, the work guides the reader through the centuries-long process of struggling for acceptance, understanding, and equality.