After completing the Doctor of Musical Arts degree in composition from Cornell University, Grant was Assistant Professor of Music at Middlebury College in Vermont from 1988-1992, where he taught composition, coordinated an American Music Week Festival each year, and directed the New Music From Middlebury concert series. In 1992, Grant left academe to compose full-time and from 1993-96 served as Composer-In-Residence to the Fairfax Symphony Orchestra in Fairfax, Virginia. In 2003, Grant completed a five-year position as Composer-In-Residence to the Bay-Atlantic Symphony in Bridgeton, New Jersey. 

Recognized by Cornell University's Graduate School of Humanities and Arts and by the Vermont chapter of the National Music Teachers Association for exceptional contributions as an educator, Grant continues to be active as a lecturer and private teacher of composition, often using Skype technology to beam in to seminar rooms and rehearsal halls for brief cyber-residencies.  

Grant's colorful musical language is known by musicians and audiences for its honed craft and immediacy. After the Kennedy Center premiere of his 45-minute work for chorus and large orchestra based on the writings of Walt Whitman, Such Was The War, the Washington Times declared it “a work of outstanding power and breadth of emotion.” The Baltimore Sun wrote, “the sincerity is never in doubt, and there's an unmistakable, cumulative power generated by the text and music. Such Was the War makes an honorable contribution to the choral repertoire.” After a November 2012 performance in Sarasota, FL, the Sarasota Herald Tribune called it “a profoundly moving artistic creation.“

After the premiere of Grant’s Concerto for Bass Clarinet and Strings by the Milwaukee Symphony Orchestra, the Milwaukee Journal Sentinel commented on a follow-up performance by the Milwaukee Chamber Orchestra: “Grant here has made music that is structurally smart, emotionally probing, rhythmically clever and harmonically subtle…. The momentum builds to some hair-raising hyena howls that had the audience howling back in approval when the 15-minute concerto ended.”

The 2009 CD release of Grant’s recital music for viola (MS1335) by violist Michelle LaCourse, Chocolates, generated universal praise, eliciting such comments as: “Grant creates a world in which the viola is completely at home, and thus can shine, yet he does it with a consistent, convincing language and a sure sense of compositional construction.”  A review of the 2013 CD release of High Autumn, recital and chamber music for clarinet (PM1028) featuring clarinetist William Helmers spoke of "whimsical . . . character-filled [music] . . . reflects Grant's deep understanding of American jazz, pop songs, art songs, and a whole host of other genres."

Grant’s ability to compose music appropriate to specific levels of experience has found him working with groups ranging from professional orchestras, choruses, solo recitalists, new music ensembles and ballet companies to community choruses, university choral and instrumental ensembles, and youth orchestras. His music is regularly programmed at music festivals, symposia, and clinics; and his desire to design new music for a given repertoire and specific instrumentation has led to many successful consortium commissions, a concept championed by the composer.

In 2011, Grant completed his Double Concerto for Euphonium and Tuba, for a consortium of 23 solo euphoniumists and tubists and over twenty collegiate wind ensembles in the United States.  The premier performance of the Double Concerto was presented on March 25, 2012 by the Lead Commissioners of the project, the University of Arizona Wind Ensemble, under the direction of Gregg Hanson, conductor, with euphoniumist Kelly Thomas and tubist Mark Nelson as featured soloists; and the work later was featured at the June 2012 International Tuba/Euphonium Conference in Linz, Austria.

Other large ensemble commissions have included Concerto for Alto Saxophone and Orchestra, for virtuoso saxophonist David Stambler; Eja! Eja! for timpani, soprano solo, large chorus and orchestra for the Choral Arts Society of Washington's Kennedy Center Holiday Concert; Tribute: Those Who Serve, for a consortium of 23 high school and collegiate bands; At Peace: Commemoration for Grade 3/4 band, composed with his colleague Debra Alexander under their nom de plume “Alison Stuart;” and Scout, for narrator and orchestra, for the Great Lakes Chamber Orchestra, based on Harper Lee’s novel To Kill a Mockingbird.

Other projects have included a chamber orchestra version of his choral symphony, Such Was The War, commissioned by the Choral Arts Society of Washington and premiered in March 2009 at the National Portrait Gallery in Washington DC as part of the Lincoln Bicentennial Celebration; tba4tet, a chamber piece for two euphoniums and two tubas commissioned by a consortium of 48 individuals and quartets; At Peace for wind ensemble, commissed by a group of collegiate wind ensembles; Whiplash for four tubas, commissioned by tubist Jim Self for the USC Bass Tuba Quartet; and Earth—poem of thanks to our common home, for orchestra, commissioned by the New South Wales Public Schools Symphony Orchestra.  More recent projects have included a 30-minute cantata for baritone solo, mixed chorus, children's chorus and chamber orchestra, Listen to the Earth, commissioned by Choral Artists of Sarasota, premiered at the Sarasota Opera House in April, 2022. 

Works by James Grant have been recorded and released by the Tasmanian Symphony Orchestra; the Iceland Symphony Orchestra; Eufonix Quartet; clarinetist William Helmers and the principal strings from the Milwaukee Symphony Orchestra; the Vermont Contemporary Music Ensemble; tubists Mark Nelson, Timothy Buzbee, and James Shearer; violist Michelle LaCourse; cellist Jonah Kim; bassoonist Mary Stuckemeyer; horn players Laura Brenes and Celeste Shearer; euphoniumist Chris Dickey; Jason Dovel, trumpet; and by Symbiosis Duo (Stacy Baker, tuba, and Gail Robertson, euphonium), In the last several years, articles on Grant's recital music and interviews with him have been featured in TUBA Journal and in the Journal of the American Viola Society. His music for tuba has been the subject of three dissertations. (See discography.)

A dual citizen of the United States and Canada, Grant lives and works in Oxtongue Lake, ON. During the summer months, Grant gets out from behind the composition desk, puts on his apron and, as The Oxtongue Baker at Dwight Market, prepares sourdough breads for the residents and guests of the Dwight/Lake of Bays region in Ontario.