[2] According to Virginia Kidd's introduction to The Best of Judith Merril, Ethel Grossman had been a suffragette, was a founder of the women's Zionist organization Hadassah, and was "a liberated female frustrated at every turn by the world in which she found herself".

[3] In 1939, Judith graduated from Morris High School in the Bronx[4] at 16 and rethought her politics under the influence of the Molotov–Ribbentrop Pact (August 23), shifting to a Trotskyist outlook.

She married Dan Zissman the next year, less than four months into a relationship that started when they met at a Trotskyist Fourth of July picnic in Central Park.

In this period, she also became one of the few female members of the New York City-based group of science fiction writers, editors, artists and fans, the Futurians, which included Kornbluth.

[2] Using her daughter's given name as a surname, Merril edited a five-page SF fanzine dated May 1945, including a letter "On Ezra Pound" by Don [sic] Zissman.

[2] Merril began editing science fiction short story anthologies in 1950 - including a "Year's Best" story-anthology series that ran from 1956 to 1967 - and published her last in 1985.

In her editorial introductions, talks and other writings, she actively argued that science fiction should no longer be isolated but become part of the literary mainstream.

[13] According to science fiction scholar Rob Latham, "throughout the 1950s, Merril, along with fellow SF authors James Blish and Damon Knight had taken the lead in promoting higher literary standards and a greater sense of professionalism within the field.

Manuscripts were workshopped at these avid gatherings, thus encouraging more care in the planning of stories, and a sense of solidarity was promoted, eventually leading to the formation of the Science Fiction Writers Association."

However, "disaffected authors began griping about a 'Milford Mafia' that was endangering SF's unique virtues by imposing literary standards essentially alien to the field.

[16] In the late 1960s, Merril moved to Toronto, Ontario, Canada, citing what she called undemocratic suppression of anti-Vietnam War activities by the U.S. government.

From the mid-1970s until her death, Merril spent much time in the Canadian peace movement, including traveling to Ottawa dressed as a witch in order to hex Parliament for allowing American cruise missile testing over Canada.

Elisabeth Carey (NESFA, 2008) Merril wrote the "Books" column of the monthly The Magazine of Fantasy & Science Fiction, March 1965 to February 1969.