Sister Pauline McShain, 90, of Rosemont, the daughter of a wealthy Philadelphia contractor who could have led a life of luxury at her family’s estate in Ireland but chose to become a nun, an educator, and, later, a philanthropist, died Friday, March 8, of complications from pneumonia at Bryn Mawr Hospital.

Born in Philadelphia, Sister Pauline, known as “Polly,” was the only child of Mary Horstmann and John McShain. Her father owned one of America’s leading construction companies, John McShain Inc. From the 1930s to the 1960s, he was the prime contractor for 100 buildings in Washington, including the Pentagon, Jefferson Memorial, and John F. Kennedy Center for the Performing Arts. He funneled his wealth into the John McShain Charities, which underwrote many Catholic causes.

Sister Pauline graduated in 1946 from the Academy of the Holy Child in Suffern, N.Y., and that year entered the Society of the Holy Child Jesus. She made her first vows in 1949 and her final vows in 1954.

Sister Pauline inherited the giving spirit of her parents, said Sister Mary Ann Buckley, a friend in the Society of the Holy Child Jesus. “Sister Polly loved both her extended family and her Holy Child community with great affection and loyalty; she dedicated her life to the service of others in diverse ways, both nationally and internationally.”

Sister Pauline taught elementary school at Oak Knoll School of the Holy Child in Summit, N.J., in the early 1950s. She taught English and religion at the Holy Child School in Rosemont starting in 1952 and served as the first principal of Holy Child’s senior school from 1956 to 1966.

Former Inquirer reporter Sally A. Downey remembered Sister Pauline as a gifted English teacher.

“She loved diagramming sentences all over the blackboard, and it drove me crazy, but I learned,” Downey said.

Sister Pauline trained new members of the Sisters of the Holy Child Jesus in the late 1960s before going to Lagos, Nigeria, where she lectured from 1971 to 1973 at the National Institute of Religious Education.

“She got what she told us was her dearest wish when she briefly became a missionary in Africa,” Downey said.

The religious society sent Sister Pauline to Catholic dioceses in White Plains, N.Y., Bridgeport, Conn., and Newark, N.J., where she worked in various roles from 1976 to 1986.

She was elected to the Society of the Holy Child Jesus General Council, and lived in Rome for six years ending in 1992. While she was serving on the council, her father died in 1989.

Her mother was living in Killarney House, County Kerry, Ireland, an estate with 25,000 acres that the McShains had acquired in 1956. As her mother’s health declined, Sister Pauline spent time at the home, supervising her mother’s care and managing the property.

After her mother died in 1998, Sister Pauline moved to Rosemont, where she served as president of the John McShain Charities before closing the organization in 2000. The Killarney House and grounds were sold to Ireland for a nominal fee and have become a national park.

In the 2000s, Sister Pauline volunteered at Siloam, a nonprofit in Philadelphia that serves people living with HIV/AIDS. In 2013, she moved to Holy Child Center in Rosemont, a retirement facility. She read and followed world and church events.

Sister Pauline earned a bachelor of arts degree in English from Rosemont College in 1958; a master of arts in secondary education from Villanova University in 1959; a master of arts in religious studies from Catholic University of America in 1971; and a master of science in pastoral counseling from Iona College in 1980.

She served on the boards of Rosemont College, Ireland’s Heritage Preservation Foundation, St. Joseph’s Preparatory School, the Philadelphia Museum of Art, and the Hagley Museum and Library.

She is survived by many cousins.

A viewing starting at 9:45 a.m. Saturday, March 16, will be followed by an 11 a.m. Mass of Christian Burial at St. Thomas of Villanova, the Rosemont Chapel, 1229 E. Lancaster Ave., Bryn Mawr. Burial will be at Calvary Cemetery, West Conshohocken.

Memorial donations may be made to the Society of the Holy Child Jesus, American Province, 1341 Montgomery Ave., Rosemont, Pa. 19010, or via www.shcj.org/american/donate/.