Lesbian's marginalised position within the New York Gay Liberation Front had led Shelley, Brown and others to form a lesbian caucus, "GLF Women". Women from GLF caucus, together with lesbians form the women's liberation movement, then formed the "Lavender Menace" in 1970.

This group is most famous for producing the first lesbian feminist manifesto, "Teh Woman-identified Woman", and for their "zap" of the Second Congress to Unite Women, held in New York (1970). The zap, in wich "Lavender Menace" members disrupted the proceedings of the Congress, called for the women's movement to fae its own homophobia and support lesbian rights.

The pertext for this action was the National Organisation for Women's recent purge of lesbian office holders according the view that the presence of lesbians in the women's movement undermined its credibility and that the lesbian issues were a distraction from the legitimate concerns of feminists and feminism.

In 1971, under increasing pressure from within and outside the women's and lesbian movements, the National Organisation for Women included lesbian rights in its charter.

Martha Shelley's influential writings in the late 1960s and early 1970s include Notes of a Radical Lesbian, Gay is Good, and Lesbianism in the Women's Liberation Movement.

In April 2004, Martha Shelley married her partner Sylvia Allen in the brief window such weddings were allowed in San Francisco.