This Day In History : December 15

1973 United States

American Psychiatric Association Declares Homosexuality Not a Mental Illness

On December 15, 1973, the American Psychiatric Association (APA) voted to remove homosexuality from its Diagnostic and Statistical Manual of Mental Disorders (DSM), officially declaring that homosexuality is not a mental illness. This decision was a pivotal moment in LGBTQ+ rights and mental health advocacy, influencing societal views and professional practices worldwide.

Also on This Day in History December 15

Discover what happened on December 15 with HISTORY's summaries of major events, anniversaries,
famous births and notable deaths.

Births on This Day, December 15
  • 1852 Henri Becquerel

    Antoine-Henri Becquerel was a French physicist who discovered radioactivity in fluorescent salts of uranium.

  • 1834 Charles Augustus Young

    American astronomer who made the first observations of the flash spectrum of the Sun, proved the gaseous nature of the sun's corona and discovered the reversing layer of the solar atmosphere.

  • 1832 Gustave Eiffel

    French civil engineer who specialized in metal structures, known especially for the Eiffel Tower in Paris.

  • 1861 Charles E. Duryea

    Charles Edgar Duryea was an American inventor who with his brother J. Frank Duryea built the first automobile with multiple copies manufactured in the U.S.

  • 1869 Joseph Barrell

    American geologist who extended ideas on sedimentary rocks made by marine sedimentation to modification by the action of rivers, winds, and ice.

Deaths on This Day, December 15
  • 1970 Ernest Marsden

    British-born New Zealand nuclear physicist who worked under Ernest Rutherford investigating atomic structure with Hans Geiger.

  • 1857 George Cayley

    (6th Baronet ) English aeronautical pioneer who built the first successful man-carrying glider (1853).

  • 1984 Frank Harold Spedding

    Frank Harold Spedding was a Canadian-American chemist. He was a renowned expert on rare earth elements, and on extraction of metals from minerals.

  • 1971 Paul Lévy

    Paul Pierre Lévy was a French mining engineer and mathematician. He contributed to probability, functional analysis, partial differential equations and series.

  • 1958 Wolfgang Pauli

    Wolfgang Ernst Pauli was an Austrian theoretical physicist and one of the pioneers of quantum physics.


Silver Bridge collapse

In 1967, the Silver Bridge between Point Pleasant, WV, and Gallipolis, OH, collapsed, died 46 people.

Street cleaning machine

In 1854, Philadelphia residents were amazed as the first practical street cleaning machine was put into operation this day.


In 1612, Simon Marius (who named Jupiter's 4 inner satellites) was the first to observe Andromeda galaxy through a telescope.

Space maneuvers

In 1965, two U.S. manned spacecraft, Gemini 6 and Gemini 7, maneuvered to within 10 feet of each other while in orbit.
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