Best known for his wind ensemble compositions, Maslanka published over 150 pieces, including ten symphonies, eight of them for concert band, over 15 concerti, and a full Mass.

[2] During his undergraduate work, Maslanka also spent one year studying abroad at the Mozarteum in Salzburg, Austria (1963–64).

Maslanka's Tenth Symphony (for concert band) was completed by his son Matthew, and received its premiere on 3 April 2018, by the University of Utah Wind Ensemble, Salt Lake City.

Maslanka received five residency fellowships at the MacDowell Colony in Peterborough, New Hampshire (1974, 1975, 1978, 1979, and 1982), as well as generous grants from the University of Connecticut Research Foundation, the American Music Center, the Martha Baird Rockefeller Fund for Music, the State University of New York Research Foundation, and the American Society of Composers, Authors, and Publishers (ASCAP).

Among these pieces are A Child's Garden of Dreams, Rollo Takes a Walk, Hymn for World Peace, numerous concertos featuring a wide variety of solo instruments, including euphonium, flute, piano, marimba, alto saxophone, and (most recently) trombone.

Having spent his childhood in the New England area, several of Maslanka's compositions were influenced by his close relationship with the ocean.