Rosalyn Tureck, a pianist and harpsichordist who played an important part in the revival of interest in the music of Johann Sebastian Bach, and who devoted more than six decades to performing, researching, teaching and writing about his works, died on Thursday at her home in Riverdale, the Bronx. She was 88.

Ms. Tureck, born in Chicago, spent many years living in London, where she acquired a regal bearing and the hint of an upper-crust British accent. She was as comfortable in literary and scientific circles as in musical ones, and was ahead of her time in arguing for a view of Bach, and of music-making, that drew on scholarship, yet was entirely nondogmatic and even fairly freewheeling.

She could argue, for example, that it was crucial to understand Bach not as a modern thinker, or as the beginning of music as we know it today, but as the peak of musical development from medieval times through the Protestant Reformation. In the same discussion, though, she could speak enthusiastically about performances of Bach on electronic instruments.

Early in her career, before she decided to focus entirely on Bach, she was an avid interpreter of contemporary music and a composer herself, although she did not perform her works publicly. And because she studied as a child with Jan Chiapusso, a Dutch-Italian concert pianist born in Java, she was introduced to the sounds of the gamelan and a variety of Asian and African instruments decades before the current interest in world music.

Ms. Tureck was born on Dec. 14, 1914, and became interested in the piano when she was 4. An intuitive musician with perfect pitch, she learned the instrument at first by imitating what she heard at an older sister's piano lessons. Her first teacher was Sophia Brilliant-Liven, a Russian pianist who had been a teaching assistant to Anton Rubinstein. Ms. Tureck studied the Romantics with her, as well as Bach, Scarlatti, Mozart and late-19th- and early-20th-century Russian composers.

In those days, Bach was widely considered to be primarily didactic music, good for developing students' hand muscles but too dry for the concert hall. Ms. Tureck, though, was fascinated by his work, and at 14, when she began studying with Chiapusso, she made a point of memorizing a prelude and fugue from "The Well-Tempered Clavier" between lessons. Chiapusso was the first to suggest that she specialize in Bach, and although she continued to study the full range of the piano repertory, she also began to focus on Bach's music, as well as his techniques of ornamentation and the kinds of instruments he used.

When she was 16, Ms. Tureck moved to New York to study with Olga Samaroff at the Juilliard School, and immediately declared her interest in focusing on Bach. Samaroff was encouraging, but others were not. When she entered the Naumburg Competition, she made it to the finals and presented an all-Bach program as her closing recital. As she told the story years later, the members of the jury said they could not give her the award "because they were sure that nobody could make a career in Bach."

Ms. Tureck's first public performance in New York was not as a pianist, but as a soloist on the theremin, an electronic instrument played by moving one's hands through an electronic field, usually between two metal poles. She played a Bach concerto. Her first real splash, however, was at Town Hall in November 1937, when she played six all-Bach concerts, a series regarded as daring, but that began to win her a following. She also maintained a parallel career, playing recitals of Chopin, Scriabin and Debussy, and in the 1940's, she performed Brahms and Beethoven concertos with the Philadelphia Orchestra and the New York Philharmonic.

Ms. Tureck continued to pursue her interest in new music as well. She gave the premieres of works written for her by David Diamond, William Schuman and Vittorio Giannini, and the European premieres of works by Aaron Copland and Wallingford Riegger. She also formed Composers of Today, an organization dedicated to bringing composers and performers together. Under its auspices, works by Messiaen, Krenek and Hovhaness were given their first New York performances. The group sponsored a concert by the composer Vladimir Ussachevsky that is said to have been the first program of taped electronic music in the United States.

In the late 1950's, though, Ms. Tureck began shedding her activities that did not relate to Bach. Since 1947, she had been spending more time in Europe, where the demand for her Bach concerts was greater than in the United States. In 1957 she moved to London, where she formed a chamber orchestra, the Tureck Bach Players, as well as the International Bach Society, meant to be a forum in which musicologists and performers could exchange ideas. In 1981 she started another organization with a similar mission, the Tureck Bach Institute.

Ms. Tureck returned to New York in 1977, after 20 years abroad, and announced her arrival with a 40th-anniversary celebration of her Town Hall Bach series, performed at Carnegie Hall. She opened the series with two performances of the "Goldberg Variations" in one evening: first on the harpsichord, then on the piano. The focus of her career, however, continued to be Europe, and in the 1980's she moved back to England, returning to New York only in the fall of 2001.

She continued to make recordings, including a series for the VAI label, as well as one of her signature pieces, the "Goldberg Variations," for Deutsche Grammophon in 1998. In recent years, Deutsche Grammophon also reissued some of her classic Bach recordings, including her 1953 account of "The Well-Tempered Clavier." She published numerous articles on Bach, as well as a three-volume collection of studies, "An Introduction to the Performance of Bach."

Ms. Tureck is survived by a sister, Sonya Goldsmith, of Pittsburgh, and two nephews, Dr. Alan Bramowitz, of Pittsburgh, and Dr. Stewart Bramson, of Grasonville, Md.

She was scheduled to perform on Thursday evening at the International Keyboard Institute and Festival at Mannes College of Music in Manhattan, but had to withdraw when she became ill. Instead, the college presented a tribute to her, which she was unable to attend. A friend, Rabbi David M. Posner, said she died a few minutes after the tribute ended.