In June 1986, Sally Mack traveled from her Brookline home to Nevada, where she, her husband, and their three sons joined nearly 150 others to protest the build-up of nuclear arms and to advocate for a test ban treaty.

“We held hands and walked as a family across the boundary of the Nuclear Test Site, where our nation’s nuclear weapons are tested in underground tunnels,’’ she wrote in a chapter for “Psychology and Social Responsibility,’’ a 1992 book.

She knew that trespassing on restricted land would lead to arrests and handcuffs. For her, it was also a symbolic step. “In the past I had always stood at the edge of nuclear terror, supporting others in my family who were more involved and active, but too busy with other very worthy causes to be active myself,’’ she wrote. “What I really had been too busy to be was in touch with my own emotions. It was liberating to experience them and then act on them and thus feel mastery over the emotions I had been avoiding.’’

Ms. Mack, who as a social worker helped create innovative programs at Greater Boston hospitals, died of cancer March 24 in hospice care at her home in Newton’s Lasell Village senior community. She was 82 and previously lived in Brookline and Cambridge.

Recalling her experience on that 115-degree day in Mercury, Nev., and the five days she subsequently spent in jail, she wrote that engaging in civil disobedience also changed her professionally.

“In my social work practice, I find that I now have a greater awareness of social, political, and spiritual issues in the lives of people I work with — and more willingness to address them and help others do so. I am less afraid of helping others face feelings of rage and despair — not surprisingly, because I am now better able to face them in myself.’’

Early in her career, she worked at what was then Beth Israel Hospital, where her colleagues included Dr. John Reichard. He recalled in an interview that when he founded Faulkner Hospital’s psychiatry department in the mid-1960s, she was the first person he hired. Ms. Mack soon launched a group for young mothers who needed to discuss with peers the challenges of raising children.

“Her work with this group provided quite an eye-opening demonstration of the powerful beneficial effect a modest psychiatric intervention could have when it was applied at one of life’s crucial development moments,’’ Reichard wrote in a tribute.

Ms. Mack later was a social worker in the neonatal intensive care unit at Children’s Hospital, advocating for the rights of parents to make crucial decisions about babies who are born prematurely and have little chance of a healthy life. Her work brought an award for excellence from the National Association of Perinatal Social Workers.

At Massachusetts General Hospital, she helped create the “Schwartz Center Rounds,’’ in which doctors, nurses, chaplains, and social workers meet to reflect on the emotional and social challenges they face while caring for patients. The program, coordinated through the Schwartz Center for Compassionate Healthcare in Boston, is used by more than 500 medical facilities in the United States, Canada, and the United Kingdom.

“I was so struck by the gentleness with which she made room for these different clinicians,’’ said Andrea Waldstein, a friend and social work colleague. “She helped care for the caregivers, I would say.’’

The younger of two children, Sally Stahl grew up in Oil City, a small community in northwestern Pennsylvania. Her father, Julius Stahl, sold real estate and insurance. Her mother, the former Mary Cohen, was a homemaker.

There were few Jewish families in town as she grew up during World War II, and though the local anti-Semitism was muted, “being accepted and being loved by others was very important to her,’’ her son Tony of Cambridge said.

She started out as pre-med at the University of Michigan and switched to majoring in social work, graduating in 1955. While at college, she began attending Quaker meetings. After graduation, she went to Israel to work with Israelis and Palestinians through the American Friends Service Committee, which left a lasting impression.

“She was committed to peace in Israel the rest of her life, and the rights and interests of Palestinians,’’ her son said. “Even though she was a Zionist, her heart was equally invested in the plight of Palestinians.’’

Upon returning home she received a master’s in social work at the University of Michigan and began her career at Beth Israel, where she met Dr. John Mack, a psychiatrist. They married in 1959 and moved to Japan for two years for his military commitment. That time stayed with her aesthetically. Once back in Greater Boston, her son said, “she had Japanese gardens inside and outside the house; there was Japanese art everywhere,’’ along with Japanese figurines and scrolls decorating walls.

With her husband, Ms. Mack was a dedicated peace activist. He taught at Harvard Medical School and was awarded the 1977 Pulitzer Prize for biography for “A Prince of Our Disorder: The Life of T.E. Lawrence.’’ The couple’s marriage ended in divorce, and Dr. Mack later encountered controversy with his books on people who said they had encountered extraterrestrials, including his 1994 bestseller “Abduction.’’ Dr. Mack died in 2004 after being struck by a vehicle as he crossed a London street while attending a conference on Lawrence.

When Ms. Mack was diagnosed with breast cancer, and later learned that the cancer had metastasized elsewhere, including in her brain, her thoughts were always with how others would cope. “The thing that was most significant about my mom was her compassion. She was someone who cared so much about people,’’ her son said.

He added, “It was her instinct to think, ‘Where can I put my compassion?’ She was somebody who came to tears very easily about someone else’s suffering. I saw her cry a number of times, but I never in my entire life saw her cry for herself.’’

In addition to her son Tony, Ms. Mack leaves two other sons, Danny of Boulder, Colo., and Ken of Bethesda, Md.; her partner, Irving Exter of Newton; and four grandchildren.

A memorial service will be held at 5:30 p.m. May 21 at deCordova Sculpture Park and Museum in Lincoln.

Ms. Mack “was the kind of person that if you sat down with her, you might end up telling her all your problems,’’ her former colleague Reichard said. “Some people are natural-born therapists.’’

Waldstein, Ms. Mack’s social work colleague, said that “it was like sitting in the sunshine to be with Sally. I didn’t ever feel any sharp edges around her.’’

In personal relationships and in political activism, Ms. Mack “had a strength for getting people enthusiastic and getting people on board,’’ said Carolyn Toll Oppenheim of Northampton, who worked with her on Israeli-Palestinian peace activism.

Part of that strength was Ms. Mack’s presence. “She had the most incredible smile that just burned warmth into you,’’ Oppenheim said. “You could hear that smile on the phone. It did something to make you feel valued and special.’’

Bryan Marquard can be reached at bryan.marquard@globe.com.