The following is a timeline of lesbian, gay, bisexual, and transgender (LGBT) history in the 20th century.
1900s
1901 – On 8 June 1901, two women, Marcela Gracia Ibeas and Elisa Sanchez Loriga, attempted to get married in A Coruña (Galicia, Spain). To achieve it Elisa had to adopt a male identity: Mario Sánchez, as listed on the marriage certificate. 1903 – In New York City on 21 February 1903, New York police conducted the first United States recorded raid on a gay bathhouse, the Ariston Hotel Baths. 34 men were arrested and 12 brought to trial on sodomy charges; 7 men received sentences ranging from 4 to 20 years in prison. 1906 – Potentially the first openly gay American novel with a happy ending, Imre, was published. Karl M. Baer, in December 1906, became the first transgender person to undergo sex reassignment surgery. 1907 – Adolf Brand, the activist leader of the Gemeinschaft der Eigenen, working to overturn Paragraph 175, published a piece "outing" the imperial chancellor of Germany, Prince Bernhard von Bülow. The Prince sued Brand for libel and cleared his name; Brand was sentenced to 18 months in prison. 1907–1909 – Harden–Eulenburg affair in Germany
1910s
1910 – Emma Goldman first begins speaking publicly in favor of homosexual rights. Magnus Hirschfeld later wrote "she was the first and only woman, indeed the first and only American, to take up the defense of homosexual love before the general public." 1912 – The first explicit reference to lesbianism in a Mormon magazine occurred when the "Young Woman's Journal" paid tribute to "Sappho of Lesbos"; the Scientific Humanitarian Committee of the Netherlands (NWHK), the first Dutch organization to campaign against anti-homosexual discrimination, is established by Dr. Jacob Schorer. 1913 – The word faggot is first used in print in reference to gays in a vocabulary of criminal slang published in Portland, Oregon: "All the faggots [sic] (sissies) will be dressed in drag at the ball tonight". 1917 – The October Revolution in Russia repeals the previous criminal code in its entirety—including Article 995. Bolshevik leaders reportedly say that "homosexual relationships and heterosexual relationships are treated exactly the same by the law." 1919 – In Berlin, Germany, Doctor Magnus Hirschfeld co-founds the Institut für Sexualwissenschaft (Institute for Sex Research), a pioneering private research institute and counseling office. Its library of thousands of books was destroyed by Nazis in May 1933. 1919 - Different from the Others, one of the first explicitly gay films, is released. Magnus Hirschfeld has a cameo in the film and partially funded its production.
1920s
1921 – In England, an attempt to make lesbianism illegal for the first time in Britain's history fails. 1922 – A new criminal code comes into force in the USSR officially decriminalizing homosexual acts. 1923 – The word fag is first used in print in reference to gays in Nels Anderson's The Hobo: "Fairies or Fags are men or boys who exploit sex for profit." 1923 – Lesbian Elsa Gidlow, born in England, published the first volume of openly lesbian love poetry in the United States, titled "On a Grey Thread." 1924 – The first homosexual rights organization in America is founded by Henry Gerber in Chicago— the Society for Human Rights. The group exists for a few months before disbanding under police pressure. Paraguay and Peru legalize homosexuality. 1926 – The New York Times is the first major publication to use the word homosexuality. Iconic lesbian café Eve's Hangout in Greenwich Village closed after police raid. 1927 – Karol Szymanowski, Poland's openly gay composer, is appointed chief of Poland's state-owned national music school, the Fryderyk Chopin Music Academy. 1928 – The Well of Loneliness by Radclyffe Hall is published in the UK and later in the United States. This sparks great legal controversy and brings the topic of homosexuality to public conversation. 1929 – On 22 May, Katharine Lee Bates, author of America the Beautiful, dies. On 16 October, a Reichstag Committee votes to repeal Paragraph 175 ; the Nazis' rise to power prevents the implementation of the vote.