Sister Nora and her cohort have gained access to some of the most illustrious boardrooms in America. Robert J. Stevens, the chief executive of Lockheed Martin, has lent her an ear, as has Carl-Henric Svanberg, the chairman of BP. Jack Welch, the former chief executive of General Electric, was so impressed by their campaign against G.E.’s involvement in nuclear weapons development that he took a helicopter to their convent to meet with the nuns. He landed the helicopter in a field across the street.

The Sisters of St. Francis are hardly the only religious voices challenging big business. They have teamed up on shareholder resolutions with other orders, including the Sisters of Charity of St. Elizabeth and the Sisters of St. Dominic of Caldwell, both in New Jersey. The Interfaith Center on Corporate Responsibility, the umbrella group under which much of Sister Nora’s activism takes place, includes Jews, Quakers, Presbyterians and nearly 300 faith-based investing groups. The Vatican, too, has weighed in with a recent encyclical, condemning “the idolatry of the market” and calling for the establishment of a central authority that could stave off future financial crises.

“Companies have learned over time that the issues we’re bringing are not frivolous,” said the Rev. Seamus P. Finn, 61, a Washington-based priest with the Missionary Oblates of Mary Immaculate and a board member of the Interfaith Center. “At the end of every transaction, there are people that are either positively or negatively impacted, and we try to explain that to them.”

On a recent Saturday morning, 12 members of the Sisters of St. Francis shareholder advocacy committee gathered in Our Lady of Angels, a cavernous, hushed building housing 80 nuns that if not for the eerie quiet would resemble an Ivy League dorm. As three nuns talked in the foyer, their tales of nieces and nephews echoing through the halls, the advocacy group, which includes several lay people, gathered in the Assisi Room for its quarterly meeting.

After a prayer, a group recitation from Psalm 68 (“The protector of orphans and the defender of widows is God in God’s holy dwelling”) and a round of applause for a nun celebrating her 50th anniversary, or golden jubilee, as a member of the order, they settled down to business.

Sister Nora, in a gray-checked jacket and a pink blouse overlaid with a necklace bearing the Franciscan cross known as a Tau, began by updating the group on its finances. In addition to its shareholder advocacy program, the committee has a social justice fund from which it allocates low-interest loans, in amounts up to $60,000, to organizations that fit with its mission. This quarter, it lent money to the Disability Opportunity Fund, a nonprofit that helps the disabled; and the Lakota Funds, a group trying to finance a credit union on a Native American reservation in South Dakota.

Image Sister Kate O'Donnell makes a point at a session. The group provides low-interest loans to like-minded organizations. Credit... Laura Pedrick for The New York Times

LATER, over lunch in the cafeteria downstairs, the Sisters of St. Francis discussed the delicate dance they face in their shareholder advocacy program — pushing corporations to change their actions, while not needling them so much on sensitive issues like executive pay that bigwigs like Mr. Blankfein, at Goldman Sachs, are not willing to meet with them.