Which publishers are noted for helping grow the repertoire of concert bands?

Hal Leonard and Alfred Music are two of the most prominent publishers in the realm of concert band literature, significantly contributing to the growth of the repertoire available for concert bands. These publishers are widely recognized for their extensive catalogs that include a variety of works, ranging from beginner to advanced pieces. Their publications often feature both contemporary and classical composers, helping educators and conductors find suitable music for their ensembles, thereby promoting a diverse concert band repertoire.

In contrast, while Boosey and Company along with Chappell have made their marks in the music publishing industry, their focus is not primarily on concert band music, which is why they do not stand out in this particular context. Schott Music and G. Schirmer are more recognized for their contributions to orchestral and vocal works rather than concert bands. Similarly, Oxford University Press and Peters, while important publishers, do not primarily specialize in concert band literature.

Thus, the correct answer emphasizes the significant contributions of Hal Leonard and Alfred Music to the concert band repertoire, which reflects the growing availability and variety of music that is important for educational and performance settings in concert bands.