In 1897, Hirschfeld founded the Scientific Humanitarian Committee which has been recognized by many historians as the first advocacy group for transgender and homosexual rights. The group aimed to overturn Paragraph 175, a clause in the German penal code instated in 1871 that criminalized homosexuality. The group argued that the law encouraged blackmail. Hirschfeld's believed that having a better understanding of homosexuality and transgenderism would eliminate societal persecution of homosexuals. Under Hirschfeld's leadership of the committee, they collected over 500 signatures from prominent Germans on a petition to abolish Paragraph 175, including Albert Einstein, Herman Hesse, and Thomas Mann. They brought the bill before the German Empire in 1898 but it had minimal support, most of which were from members of the Social Democratic Party of Germany, which was on the precipice of rebuilding its voter base at the time. Hirschfeld arranged for the bill to be reintroduced in the 1920's only to have that effort usurped by the Nazi Party.
The Institute became a hub for scientific research and piqued the interest of many scientists of sexuality, as well as scientific, political and social reformers around the world. In 1923 the Institute was visited by Nikolai Semashko, Commissar for Health in the Soviet Union. This was followed by numerous visits and research trips by health officials, political, sexual and social reformers, and scientific researchers from the Soviet Union interested in the work of Hirschfeld. In 1926 a delegation from the institute, led by Hirschfeld, reciprocated with a research visit to Moscow. When the Nazi's seized power in 1933, they attacked the Institute burning many of its books as well as the archives of research that had been gathered for over 20 years.
Magnus Hirschfeld coined the term transsexualism, identifying the clinical category which his colleague Harry Benjamin would later develop in the United States. Transgender people were on the staff of the Institute, as well as being among the clients there. Various Endocrinologic and surgical services were offered, including the first modern "sex-change" operations in the 1930s. Hirschfeld also worked with Berlin's police department to curtail the arrest of cross-dressed individuals on suspicion of prostitution.
Hirschfeld has a large bibliography, some have been lost over time and very little has been translated into English. The following is a list of works relevant to transgender issues that have been translated into English.
The Transvestites: The Erotic Drive to Cross-Dress (1910),
Homosexuality of Men and Women (1914)
The Sexual History of the World War (1930)
Men and Women: The World Journey of a Sexologist (1933)