Marietta E. Spencer, a former executive at Children’s Home Society of Minnesota, was a pioneering social worker whose research and work with families helped to revolutionize attitudes toward adoption.

A native of Austria, Spencer spent most of her adult life in Minnesota, where she touched the lives of thousands of adoptive families.

Spencer died at an assisted-living center in Roseville of natural causes. She was 95.

Spencer was perhaps best known for her 1979 article, “The Terminology of Adoption,” which fundamentally changed how social workers and others communicate about adoption. In the article, and over her 50-year career as a social worker, Spencer pressed relentlessly for clear language that demystified adoption and wiped away stigmatizing terms that made adoption appear illegitimate or suggested a lack of caring by birth parents.

In Spencer’s vernacular, there were no “real parents,” but rather “birth parents” and “adoptive parents.” Children were not “surrendered” or “given up”; instead, families made a “loving plan” for a child. While controversial at the time, Spencer’s vocabulary has been credited with helping adoption gain broader acceptance worldwide.

She was also a pioneer in the area of post-adoption services at a time when the process was still shrouded in secrecy. As program director at the nonprofit Children’s Home Society in St. Paul, Spencer crisscrossed the state holding post-adoption workshops to help families gain access to services and deal openly with issues such as rejection and abandonment. Spencer even invited unwed birth mothers to speak at her workshops, at a time when such mothers still bore a heavy stigma. From the early 1970s to the late 1980s, more than 14,000 people attended Spencer’s post-adoption workshops, according to her own records.

“Marietta was a force of nature,” said Meg Bale of Bloomington, who worked with Spencer at the Children’s Home Society. “She also had no tolerance for insensitive language around adoption. I don’t care if you were the president of the United States or the pope, she would correct you. And she didn’t mince words.”

Born in 1922, Spencer grew up in Vienna as the youngest of two children born to a merchant family in the jewelry trade. She moved to the United States during World War II after she received an academic scholarship to Reed College in Portland, Ore. While at Reed, she met her late husband, Robert Spencer, who became an acclaimed professor of cultural anthropology at the University of Minnesota.

With her professorial glasses and not-so-faint Austrian accent, Spencer would lecture audiences for hours on respectful language and the importance of adoptees learning about their birth parents. “Adoption advocacy was her life and passion,” said her son, Paul Spencer, a retired circuit board designer who now lives in Austin, Texas. “She lived and breathed it.”

Jennifer Arndt-Johns, who produced a documentary (“Crossing Chasms”) chronicling her efforts to locate her biological relatives in South Korea, recalled a “life-altering encounter” with Spencer in 1998. After a showing of the film, Spencer came up and, with a stern look, insisted on correcting a statement made by Arndt-Johns in the film.

In the documentary, Arndt-Johns said she had been “abandoned on the doorsteps of a police station” in South Korea. “Marietta literally took my hand and said, ‘I want to let you know you were not abandoned, but you were placed upon that doorstep to be found,’ ” said Arndt-Johns, a filmmaker who lives in Golden Valley. “I remember tears filling my eyes. With that single sentence, she changed my whole concept of myself. ... It was a reminder of the powerful resonance that words have.”

An invitation-only memorial service is planned.