Mary Daniel Turner SNDdeN (November 21, 1925 – January 27, 2010) was an American Catholic sister of Notre Dame de Namur and the former executive director of the Leadership Conference of Women Religious (LCWR).

Trinity gave her an honorary doctorate in 1984, with the citation that because "in her unflinching search for truth she has empowered women to believe in the possibility of a transformed world that is inclusive, collaborative and pluralistic."

[1] In a 1985 chapter titled "Woman and Power," Turner called out the Catholic church for being overly dependent on Thomas Aquinas and the outdated "erroneous biological presuppositions" of 13th-century medical thought on which he based his views of women.

In 2009 James Martin SJ summarized its lasting influence: The chasm between traditional and progressive religious life was made evident in 1992 with the publication of The Transformation of the American Catholic Sisterhood by Lora Ann Quiñonez, C.D.P., and Mary Daniel Turner, S.N.D.deN.

The book impelled Cardinal James Hickey, bishop of Washington, D.C., at the time, to travel to Rome to fight for the establishment of a congregation of women religious that would be more faithful to the church.

Hence the Conference of Major Superiors of Women Religious was formed with membership based on wearing the habit, communal prayer, eucharistic adoration and fidelity to the church.

Meanwhile, the Leadership Conference of Women Religious continued in the spirit of Vatican II to be open to the world, exploring avenues of liberation theology, feminist theology and the plight of the poor, among others.The contrast between the progressive and conservative Catholic sisters' conferences became evident in 2012, when under Pope Benedict XIV the Vatican launched what became a three-year investigation into American Catholic sisters, with a specific focus on the LCWR.

It's really a difference in values between the church of Rome and the U.S. church.She appeared in a video that the Smithsonian showed in early 2010 as part of the traveling exhibit "Women and Spirit: Catholic Sisters in America.