Masters of the Celtic harp Gráinne Hambly and William Jackson will play a concert — and offer a music therapy workshop centered on the small harp — next weekend at the Katharine Cornell Theatre on Spring street in Vineyard Haven.

Both events are on Saturday, Sept. 29 — the concert is at 8 p.m. and Mr. Jackson’s workshop is at 4 p.m.

Two of the foremost harpers of Ireland and Scotland, Ms. Hambly and Mr. Jackson combine their extraordinary talents here to start their second year touring together as The Masters of the Celtic Harp. In addition to solo harp they will also be playing together two harps, concertina, tinwhistle and bouzouki.

Over the past eight years, Ms. Hambly has not only garnered an ever-growing following of devoted harp enthusiasts but has managed to cross-over and capture the Irish music fan with the taste for the fast, driving reels and jigs of traditional music. She has broken the genteel parlor image and elevated the stature of the harp to the levels of fiddles and pipes in the realm of dynamic dance music.

Add to that the unsurpassed expressive quality the harp has in her renditions of age-old airs and laments and you have a masterful performance.

Mayo-born, now living in Galway, she has just released her third album, The Thorn Tree, which joins her two critically acclaimed compact discs, Between the Showers and Golden Lights Green Shadows, as must-haves for Irish harp fans. She has recorded with other artists and published two books of her arrangements.

Mr. Jackson of Glasgow has been at the forefront of Scottish traditional music for nearly 30 years. As well as being known as one of the leading harpers and multi-instrumentalists in Scotland, he has gained an international reputation as a composer. His Land of Light won the international competition in 1999 as the new song for Scotland.

Mr. Jackson was a founding member and creative tour de force of Ossian in 1976, which became one of Scotland’s best-loved traditional bands. The band, whose music influenced a generation of musicians, extensively toured the U.S. and Europe. He plays harp, piano, tinwhistle and mandola. While working with Ossian, he also established himself as a composer and he has steadily knit together Celtic influences with classical instrumentation in a style uniquely his own.

He has an impressive list of commissioned works and subsequent recordings, including The Wellpark Suite, St. Mungo, and Inchcolm, a 1996 commission from the Scottish Chamber Orchestra called A Scottish Island and his latest commission, Duan Albanach, created for the 2002 opening of the Celtic Connections Festival in Glasgow. He has composed music in Scotland for the BBC and Scottish television and recently directed and performed the music for The Battle of the Clans for the History Channel.

His performance on harp, whistle and bodhran is featured on the soundtrack of A Shot at Glory, starring Robert Duval and Michael Keaton, which was filmed in Scotland.

Tickets for the show can be purchased in advance for $15 (children are free) at Aboveground Records, Island Entertainment, and Alley’s General Store; at the door, tickets are $20. For details, call 508-693-6996.

Mr. Jackson also is holding a workshop called the small harp in music therapy. He trained as a music therapist at the London Guildhall School of Music, and specializes in working with children with cerebral palsy and autism.

He currently heads a music therapy program at Mission Children’s Hospital, Asheville, N.C.

For information on the workshop, call Cynthia at 508-693-1330. The workshop includes a video of active music therapy sessions with Mr. Jackson and some of his patients.