In November 1965, he persuaded Casey Hayden to let him publish under the title "Sex and Caste" a paper she had been circulating among women questioning their role and position within Student Nonviolent Coordinating Committee.

[20] That same month, November 1965, McReynolds was one of five men who publicly burned their draft cards at an anti-war demonstration at Union Square in New York.

This was one of the first public draft-card burnings after U.S. law was changed on August 30, 1965, to make such actions a felony, punishable by up to five years' imprisonment.

The smallest and the most left wing faction of the SPA, known as the Debs Caucus, including McReynolds, formed the Socialist Party USA (SPUSA).

McReynolds' primary theoretical contribution to socialism came from his blending of a pacifist world-view with a commitment to re-distributive socialist economics.

His widely read pamphlet, The Philosophy of Nonviolence, provides a unique window into the mind of a lifelong activist wrestling with the contradictions and pitfalls which plagued the political left in the 20th century.

Consequently, he mapped out a pluralistic approach which is, on the one hand, socialist, yet is entirely engaged with thought systems as seemingly contradictory as Hindu philosophy.

He concluded that a brand of pacifist-socialism is best suited for future socialist experiments since it offers the greatest opportunity to prefigure the kinds of democratic relations necessary to create a functional and free society.

[4][28] McReynolds was active politically until just before his death, attending meetings, speaking in classrooms, being interviewed for films and research, and participating in peace, justice, antiwar, and antinuclear actions.

Senator Bernie Sanders for President of the United States, praising him as a "serious candidate" and for not personally attacking his Democratic rival Hillary Clinton.