Mastering languages seemed easy for Sally Costello, who majored in French and minored in ­Russian in college and mastered German while living in Germany.

Such proficiency was useful during her 35-year career as a translator, which included tasks that ranged from translating birth certificates for Russian hockey players to translating the speeches and press conferences of Charles de Gaulle, the former president of France.

“She absolutely loved translation; it was what she was meant to do,” said her husband, Michael. “She was very, very persnickety about research, so when she’d do a translation, she wouldn’t just bang it out and send it off.”

Mrs. Costello, whose deep faith sustained her for the 18 years since she had become ill, died of breast cancer June 20 in her Rockport home. She was 69.

“She was good with both the technical knowledge and also the daily language people used,” her husband said. “She had voluminous files, and the languages just seemed to come easy to her.”

Their daughter, Heather Sullivan of Pembroke, said Mrs. Costello predicted in an eighth-grade ­essay that she would become a translator.

Her mother, she added, translated the ‘Make Way for Ducklings’ children’s book into Russian to ­accompany duck statues sent to Raisa Gorbachev, the wife of former Soviet leader Mikhail ­Gorbachev.

“She loved language and the variety of subject matters she translated,” Sullivan said. “Each job was different, and this kept her mind active and engaged.”

Born Sally Bissinger in Ithaca, N.Y., Mrs. Costello graduated from Edgewater High School in Orlando in 1960 and from the University of Florida in 1964.

Within weeks, she was working at a French Embassy press service in New York, translating de Gaulle’s speeches. Three years later, she moved to Munich to work for Radio Liberty as a researcher and translator of Russian newspaper articles.

Her future husband was working in Munich as a policy analyst for Radio Free Europe, and they ­began dating after meeting at a dinner party.

“We’d been together for 2½ years and nothing had really happened, so she packed her bags and went back to the United States,” he said. “I lasted about two weeks before I made a late-night call and asked her to marry me. She said yes, and the rest is truly history.”

They spent the first part of their 42-year marriage in Munich, where their daughter and oldest son were born, and moved to Andover in the early 1970s.

Mrs. Costello worked as a part-time translator for Transtek and later with Linguistic Systems, based in Cambridge. In 1979 the family moved to Rockport.

In 1987, she graduated from the University of Massachusetts Lowell with a master’s degree in French language teaching.

After five years as an in-house translator of French, German, and Russian for Linguistic Systems, Mrs. Costello began operating a home translation agency in 1992.

“Mrs. Costello was absolutely a big asset to the company because of her reliability and superb English writing style,” said Hugh Oechler, a colleague at Linguistic Systems.

Through the years, Mrs. Costello also had a strong spiritual life.

“It wasn’t as if there was an epiphany and all of a sudden she became a spiritual person, because she was always a spiritual person,” her husband said. “She was the kind of person that had a gift for making other people feel special, and she was very humble, very kind, and gentle.”

In the mid-1990s, Mrs. Costello converted to Catholicism, becoming friends with the Rev. Ronald J. Gariboldi, a priest at St. Joachim Church in Rockport, her husband said.

“For the next 18 years, Sally did everything in the church you could possibly do,” he said. “She was involved in daily Masses, and she was a Eucharistic minister.”

Mrs. Costello, Gariboldi said, “felt the central message of Catholicism was love, and she wanted to experience it and live it.”

Although there were about 1,400 parishioners, everyone knew her, Gariboldi said.

“You cannot enter St. Joachim without thinking of her,” he said. “She was caring, gentle, open to all, and self-sacrificing. She never had a harsh word for anyone, was a model for all of us to follow, and left her mark.”

Sullivan, who talked to her mother daily, said that after Mrs. Costello converted, her faith became a central part of her life.

“She loved starting the day with the morning Mass and turning the day over to God,” Sullivan said.

Mrs. Costello, who also participated in the church’s bereavement support group, was a nurturer with a huge heart, her daughter said.

“Sally was an incredibly remarkable woman,” her husband said. “Obviously she was my best friend, but she just had an incredible smile that was on her face constantly. She had such a positive outlook on life.”

A service has been held for Mrs. Costello, who, in addition to her husband and daughter, leaves three sons, Christopher of Rowley, Sean of Essex, and Matthew of Needham; a brother, Steven Bissinger of Orlando; two half-sisters, Gail Garman of Newmanstown, Pa., and Karen Steinrock of Grantham, Pa.; and eight grandchildren.

Though Mrs. Costello was diagnosed with cancer in 1994, few knew.

“She refused to allow cancer to affect how she dealt with the world or how the world dealt with her,” her husband said. “Lots and lots of people have said to me in the last few weeks they saw Sally at church every day or saw Sally at meetings of various groups and never knew she had cancer. She said to me over and over again, ‘I just don’t believe in cancer; I believe in God.’ She refused to give it power.”