When the family moved to Baltimore in 1918, his father joined the Socialist Labor Party (SLP) so that from an early age Reynolds was raised to accept the tenets of Marxism and socialism.

[3] After graduating from high school, Reynolds worked as a reporter for the Catskill Morning Star from 1937–38 and as editor of the weekly Oneonta News from 1939–40.

In 1937, he married his first wife, Evelyn Sandell, with whom he had three children, Emil, La Verne, and Dallas Mack Jr. From 1940 to 1943 Reynolds worked for IBM at the San Pedro, California Shipyards.

After searching for a place with a low cost of living, they moved to Taos, New Mexico, where Reynolds met science fiction writers Walt Sheldon and Fredric Brown.

In 1955, Reynolds became a correspondent for Rogue magazine and began making money writing about his travels as well as from his science fiction stories, whose socioeconomic speculations now reflected the insights gained from his encounters with other cultures.

[3] The 1960s saw some of Reynolds' best work, including the short stories "Revolution," "Combat," "Freedom," "Subversive," and "Mercenary" (which became the first installment of the Joe Mauser series), the Homer Crawford serials "Black Man's Burden" and "Border, Breed nor Birth," and the novellas "Adaptation," "Ultima Thule" (both part of the United Planet series), and "Status Quo" (a Hugo nominee).

[10] While Reynolds continued to write and sell science fiction stories, by 1969 his sales began to decline and several of his novels were held back during a takeover of Ace Books in 1970 and not published until 1975.

[3] Commune 2000 A.D., The Towers of Utopia, and Rolltown and the Lagrangia series explored marginal utopian colonies on earth and in space, respectively.

[12] Accordingly, many of Reynolds' original contributions to science fiction exist in the form of sociological predictions, some of which have come to pass: the credit-card economy, a worldwide computer network with information available at one's fingertips, a "Common Europe," a basic guaranteed income for every citizen, mobile cities, or global societies with a universal religion and an Esperanto-based common language.

[3] Reynolds sought to shake his readers' complacent acceptance of Cold War capitalism by depicting a variety of post-capitalist near futures, many of which he envisioned could occur around the year 2000.

[14] Reynolds has been called a "cautious,"[11] "critical,"[15] or "ambiguous"[3] Utopian writer because his many explorations of ideal societies, such as his updates of Edward Bellamy's Looking Backward: 2000-1887 and Equality, focus as much on Utopia's dilemmas as on its benefits.

Typically, Reynolds' Utopias are worlds of almost complete industrial automation so that no one needs to work, everyone lives in security thanks to a guaranteed basic income, and those who volunteer for the few jobs left are chosen via a quantitative ability test.

[11] At the same time, the population's very life of leisure has led to species stasis by discouraging the continual striving that gives humanity its purpose[15] as in the story "Utopian," or the Utopian welfare state has metamorphosed into a caste society where those in power aim to keep it, blocking for its other members the opportunity to exert themselves to the full extent of their abilities, as in the Joe Mauser series.