Usually the term “historical dictionary” is just another way of saying encyclopedia. But in the case of homosexuality, it was necessary to produce both an encyclopedia and a dictionary, because there is still incredible confusion—and in some cases, outright controversy—about the meanings of even the most essential terms. Yet, without having some agreement on these issues, it is impossible to achieve any deeper understanding of a field that is hardly just academic, but a matter of securing a decent life, and sometimes even any life, for those concerned. This fact becomes perfectly clear when considering the history of homosexuality, a history all too often afflicted by dogma, discrimination, and even death, and where—despite considerable progress in some places in recent decades—the situation has hardly improved or may even have gotten worse. Thus, this volume has two crucial tasks: to help us understand what we are talking about with regard to homosexuality and to see what these issues and terms mean in reality.