Composer, Orchestra Conductor, and Pianist. He was among the first conductors born and educated in the US to receive worldwide acclaim, and was one of the major figures in orchestral conducting in the second half of the 20th century. As a composer, he is best remembered for writing the music for Broadway's "On the Town" (1944), "Wonderful Town" (1953), and "West Side Story" (1957), for which he also contributed the film scores. As a conductor, he held the post as the music director of the New York Philharmonic from 1958 to 1969, becoming the first American-born conductor to hold that position. Born Louis Bernstein, he was the son of Ukrainian Jewish parents whose father was a businessman and owner of a bookstore. His parents called him 'Leonard' and when he was fifteen, he changed his name accordingly. At a very young age, he listened to a piano performance and was immediately captivated. He subsequently began learning the piano seriously when the family acquired his cousin's unwanted piano. As a child, he attended the Garrison Grammar School and Boston Latin School in Boston, Massachusetts, graduating in 1935. He enrolled in Harvard University at Cambridge, Massachusetts, majoring in music, and received in Bachelor of Arts Degree in 1939. The following year, he moved to New York City, New York, taking jobs as a music publisher, transcribing music, or producing arrangements under the pseudonym Lenny Amber. He began his study at the Boston Symphony Orchestra's summer institute, Tanglewood, in the conducting class of the orchestra's conductor, Serge Koussevitzky. In November 1943, having recently been appointed assistant conductor of the New York Philharmonic Orchestra, he made his major conducting debut at sudden notice and without any rehearsal after conductor Bruno Walter came down with the flu. He became instantly famous because the concert was nationally broadcast, and afterwards started to appear as a guest conductor with many US orchestras. From 1945 to 1947 he was the Music Director of the New York City Symphony Orchestra. He also began to emerged as a composer during this time. In January 1944 he conducted the premiere of his "Jeremiah Symphony" in Pittsburgh, Pennsylvania. His score to the ballet "Fancy Free" opened in New York City in April 1944, which was later developed into the Broadway musical "On the Town" that opened the following December. After World War II, his career on the international stage began to flourish, with his first European conducting trip in 1946. The same year he conducted an opera for the first time, with the American premiere at Tanglewood of Benjamin Britten's "Peter Grimes." This was followed by conductor Arturo Toscanini's invitation to guest conduct two concerts with the NBC Symphony Orchestra, one of which featured him as piano soloist in Maurice Ravel's "Piano Concerto in G Major." In 1947 he conducted in Tel Aviv, Israel for the first time, beginning a lifelong association with that country. During the 1950s he was blacklisted by the US State Department and CBS for his involvement in left-wing causes and organizations, but it had minimal impact on his career. From 1951 to 1956 he was a visiting music professor Brandeis University in Waltham, Massachusetts, and founded the Creative Arts Festival there in 1952. In 1953 he produced his score to the musical "Wonderful Town," and the following year he made the first of his television lectures for the CBS arts program "Omnibus." Further "Omnibus" lectures followed from 1955 to 1958 (later on ABC and then NBC) covering jazz, conducting, American musical comedy, modern music, Johann Sebastian Bach, and grand opera. In late 1956 he conducted the New York Philharmonic in concerts that were to have been conducted by Guido Cantelli, who had died in an airplane crash in Paris. Partly due to these appearances, he was named the music director of the New York Philharmonic in 1957 (he began his tenure in that position in 1958), replacing Dimitri Mitropoulos. He became a prominent figure in the US through his series of 53 televised "Young People's Concerts" for CBS, which grew out of his "Omnibus" programs. He became as famous for his educational work in those concerts as for his conducting. His "Young People's Concerts" were the first and probably the most influential series of music appreciation programs ever produced on television, and were highly acclaimed by critics. In 1959 he took the New York Philharmonic on a tour of Europe and the Soviet Union, portions of which were filmed by CBS. A highlight of the tour was Bernstein's performance of Dmitri Shostakovich's "Fifth Symphony," in the presence of the composer. In 1961 he conducted at President John F. Kennedy's pre-inaugural gala, and he was an occasional guest in the Kennedy White House and in 1968 he also conducted at the funeral mass for the late President Kennedy's brother Robert Kennedy. During the 1960s he produced his "Kaddish Symphony" (1963) dedicated to the recently assassinated President John F. Kennedy and the "Chichester Psalms" (1965) which he produced during a sabbatical year he took from the Philharmonic to concentrate on composition. In 1969 he stepped down as the full-time conductor of the New York Philharmonic and devoted more time to writing music and guest conducting, even though he continued to occasionally tour with them. His major compositions during the 1970s were his "MASS: A Theatre Piece for Singers, Players, and Dancers," his score for the ballet "Dybbuk," his orchestral vocal work "Songfest," and his U.S. bicentenary musical "1600 Pennsylvania Avenue" that was written with lyrics by Alan Jay Lerner which was his first real theatrical flop, and last original Broadway show. In 1973 he was appointed to the Charles Eliot Norton Chair as Professor of Poetry at Harvard University, and delivered a series of six televised lectures on music with musical examples played by the Boston Symphony Orchestra, which were not televised until 1976. Taking the title from a Charles Edward Ives work, he called the series "The Unanswered Question." In 1979 he conducted the Berlin Philharmonic Orchestra for the first and only time, in two charity concerts for Amnesty International involving performances of Gustav Mahler's "Ninth Symphony." In the 1980s he continued to conduct, teach, compose, and produce the occasional TV documentary. His most significant compositions during this time were probably his opera "A Quiet Place" (which he wrote with Stephen Wadsworth and which premiered (in its original version) in Houston in 1983), "Divertimento for Orchestra," and "Halil" for flute and orchestra. In 1982 he and impresario Ernest Fleischmann founded the Los Angeles Philharmonic Institute as a summer training academy. He served as artistic director and taught conducting there until 1984. In 1985 he took the European Community Youth Orchestra in a "Journey for Peace" tour around Europe and to Japan. In his later years, his life and work was celebrated around the world. On December 25, 1989 he conducted Beethoven's "Symphony No. 9" in East Berlin, Germany's Schauspielhaus (Playhouse) as part of a celebration of the fall of the Berlin Wall. The previous day, he had conducted the same work in West Berlin, Germany. The concert was broadcast live in more than twenty countries to an estimated audience of 100 million people. For the occasion, he reworded Johann Christoph Friedrich von Schiller's text of the "Ode to Joy," substituting the word 'Freiheit' (freedom) for 'Freude' (joy). In the summer of 1990, he and conductor/composer Michael Tilson Thomas founded the Pacific Music Festival in Sapporo, Japan, a summer training school for musicians. He made his final performance as a conductor at Tanglewood on August 19, 1990, with the Boston Symphony playing Benjamin Britten's "Four Sea Interludes" from Peter Grimes, and Beethoven's "Seventh Symphony." He suffered a coughing fit in the middle of the Beethoven performance which almost caused the concert to break down. In October 1990 he announced his retirement from conducting due to his health problems. During his lifetime, he received numerous awards and honors, including a Fellow of the American Academy of Arts and Sciences (1951), the Sonning (Denmark) Award (1956), the Ditson Conductor's Award (1958), the George Peabody Medal - Johns Hopkins University (1980), the Kennedy Center Honors (1980), the Ernst von Siemens Music Prize (1987), The British Royal Philharmonic Society Gold Medal (1987), Italy's Knight Grand Cross Order of Merit (1989), the Japan Arts Association Lifetime Achievement Award, the Grammy Lifetime Achievement Award, along with various other Grammy Awards for musical composition and performance.