Adler's catalog includes over 400 published works in all media including five operas, six symphonies, eight string quartets, eight concerti (organ, piano, violin, cello, flute, guitar, saxophone quartet, woodwind quintet), many shorter orchestral works, works for wind ensemble and band, chamber music, a great deal of choral music and songs. He has published three books: Choral Conducting, an anthology (Holt, Rinehart and Winston, 1971), second edition (Schirmer Books, 1985); Sight-Singing (W. W. Norton, 1979, 1997); and The Study of Orchestration (W. W. Norton, 1982, 1989), and numerous articles in major magazines and reference books here and abroad.

Since 1966, Adler has been professor of composition at the Eastman School of Music and chairman of the composition department since 1974. In 1984, he was made a Mentor of the University of Rochester. Previous to this, he was professor of composition at North Texas State University (1957-1966) and Music Director at Temple Emanu-El, Dallas, Texas (1953-1966). From 1954 to 1958 he was music director of the Dallas Lyric Theater. He has been a guest composer or conductor at over 300 universities and colleges worldwide. Adler retired from Eastman in 1994 to become Professor Emeritus of that institution. Since then he has taught at Ithaca College, University of Cincinnati, Bowling Green State University, University of Missouri (KC), University of Utah, and others. He is currently on the faculty of the Juilliard School of Music in New York City.

He has received commissions and grants from the National Endowment for the Arts (1975, 1978, 1980, and 1982), the Ford Foundation, the Rockefeller Foundation, the Barlow Foundation, the Koussevitzky Foundation, the Dallas Symphony Orchestra, the Rochester Philharmonic, the Fine Arts Quartet, the Pro Arte Quartet, the Kentucky Arts Commission, the Sinfonia Foundation, the City of Jerusalem, the Cleveland Quartet, the Welsh Arts Council, Oklahoma City Symphony, Cincinnati Symphony, and many others.

He has been awarded many prizes including a 1990 award from the American Academy and Institute of Arts and Letters, the Charles Ives Award, the Lillian Fairchild Award, etc. In 1983, he won the Deems Taylor Award for his book on orchestration; in 1984, he was appointed Honorary Professorial Fellow of the University College in Cardiff, Wales, and was awarded a Guggenheim Fellowship for 1984-85. He has been a MacDowell Fellow for five years betwen 1954 and 1963. In 1986 he received the "Distinguished Alumni Award" from Boston University. The Music Teachers' National Association selected Adler as its "Composer of the Year 1986-87" for Quintalogues, which won the national competition. In the 1988-89 year, he has been designated "Phi Beta Kappa Visiting Scholar." In 1989, he was awarded the Eastman School's Eisenhart Award for distinguished teaching, and he has been given the honor of Composer of the Year (1991) for the American Guild of Organists. During his second visit to Chile, Adler was elected to the Chilean Academy of Fine Arts (1993) "for his outstanding contributions to the world of music as composer, conductor, and author."

His works have been performed by major symphonic, choral and chamber organizations in the U.S., South America, Europe, Asia, and Israel including the New York Philharmonic, the Chicago Symphony, the Philadelphia Orchestra, the Dallas Symphony, the Boston Pops, the Houston Symphony, the Detroit Symphony as well as the orchestras of Kansas City, San Antonio, Ft. Worth, New Orleans, Cincinnati, St. Louis, Los Angeles, and others.

Adler has also appeared as conductor with major orchestras both here and abroad and his compositions have been recorded on RCA, Vanguard, Crystal, CRI, Lyrichord, Mark, Turnabout, Gasparo, and Golden Crest Records.