Seamus EganWhen you’re the music director for “A Christmas Celtic Sojourn,” says Seamus Egan, Christmas comes early. “Actually,” he quips, “Christmas tends to last all year.”

Egan is finishing up his first decade overseeing the musical end of things for the popular holiday-themed showcase of music, dance, songs, and stories in the Celtic tradition, which takes place for the 14th year this month with performances in Providence, New Bedford, Worcester, and Rockport, as well as its run at the Cutler Majestic Theatre in downtown Boston [the schedule is available at wgbh.org/celtic].

A virtuoso on banjo, flute, mandolin, whistle and guitar, Egan will once again be performing at the show with members of Solas, the Irish-American super-group he co-founded. Also returning to “Christmas Celtic Sojourn” are harpist Maeve Gilchrist, singer Eilís Kennedy and cellist Natalie Haas, as is dancer Cara Butler – newly minted as the show’s dance director – and her longtime partner, Nathan Pilatzke, as well as the Harney Academy of Irish Dance. New to the roster is the Acadian trio Vishten.

And serving as host and interlocutor will be the “Christmas Celtic Sojourn” creator, Brian O’Donovan of WGBH-FM’s “A Celtic Sojourn,” which serves as a template for the show.

Last month, finishing up a tour with Solas, Egan paused to reflect on his tenure with “Christmas Celtic Sojourn,” and what the annual three-week interval – from rehearsal to final bow – encompasses.

“When I started, the show wasn’t as involved as it is now – definitely had less moving parts,” he says. “When Brian spoke to me about becoming music director, he had a desire to have ‘Christmas Celtic Sojourn’ be a show, rather than a concert. He was looking for a consistency, a unified vision for how things should run, which would require a lot of planning and coordination – not just gathering people the day of the event.”

In fact, the planning process for the next “Sojourn” begins not all that long after the curtain falls on the previous show’s final performance: Given the busy schedules of high-caliber performers who appear in “Christmas Celtic Sojourn,” it’s a necessity to start identifying potential candidates well ahead of time. As this goes on, Egan says, he will have regular conversations with O’Donovan, artistic director Paula Plum, and the dance director – in this case, Butler.

“For me, the main job is knowing who we have playing and singing,” he says. “That’s how I can start to figure out arrangements – what’s a ‘highlight’ as opposed to a full ensemble performance, for example, or which song or tune set should go where. I want to plan a nice musical arc while contemplating the overall plan for the show.”

E-mail, Skype, and other technology has made it easier to discuss or experiment with musical ideas over long distances, but for Egan the work doesn’t really begin in earnest until that first day that the musicians and singers are gathered in the Cutler Majestic practice room.

“It is kind of like waking up on Christmas morning,” laughs Egan. “You go into that room, and there are all these brilliant people there and you think to yourself, ‘Oh, this is fantastic!’”

But there’s not much opportunity for ooh-ing and aah-ing, because it’s time to roll up sleeves and get down to business. And this is where the individual and collective creativity truly starts to flow: Egan doesn’t have written parts to hand out – he doesn’t read or write music, and in any case that’s not the approach he prefers.

“I come in with some concepts. I might say to Maeve [Gilchrist], ‘OK, I want the harp to do this,’ and she’ll instantly have a far better idea as to how to accomplish what I might have in my head. See, that’s what this all comes down to: These are all excellent musicians and singers, and you trust what it is that they do. It definitely helps to have some notions beforehand, but ultimately you stay out of the way and let it happen, and you take advantage of the uniqueness that someone brings.”

By now, Egan’s pretty well used to having these type of leadership roles, whether for “Christmas Celtic Sojourn” or other collaborations, and he’s learned a thing or two. “There’s always way less time than you hope for, and probably more people than you’re prepared to work with,” he says, “so the equation is usually the opposite to what it should be. Really, it all comes down to what happens in that rehearsal room – that has to work most of all.”

Fortunately, it has worked in “Christmas Celtic Sojourn,” he says. “There’s a moment I really love, when I watch someone give just a fantastic performance. We’ve been doing all this work, and you know that this person gets it, and then you see him or her achieve a whole other level. That’s the mark of a truly great performer: They take whatever rough idea I might have and make it completely their own.”

Says O’Donovan, “Seamus has been a big part of the artistic growth of the show over the years.  His sensitivity to the tradition, combined with an ear for contemporary context is pretty unique, and we have benefited greatly as a result.  He also has a unique way of working with musicians in what can be a stressful period of bringing things together before the show opens.  I am so lucky to have him as a partner in this endeavor.”

Here’s a look at the performers Egan will be collaborating with in this year’s “A Christmas Celtic Sojourn”:

• Certainly the most familiar faces for Egan will be Solas mates fiddler Winifred Horan and guitarist Eamon McElholm, with special guest accordionist Johnny Connolly; they’ll be aided by bassist Chico Huff and percussionist Steve Holloway. The boundary-pushing band recently wrapped up its 20th anniversary year, which included an extensive tour and the release of a new album, “All These Years,” featuring appearances by former members like John Doyle, Karan Casey, Deirdre Scanlan and John Williams.

• Scottish native Maeve Gilchrist, a one-time resident of Boston and former student at Berklee College of Music, is known for the jazz and world-music influences she brings to her interpretation of Irish and Scottish traditions. Among her ongoing collaborations are with dancer Nic Gareiss, and bluegrass fiddler Darol Anger.

• Natalie Haas, recently returned to the Boston area after several years in Montreal, who has been a major reason for the cello’s emergence as a “Celtic” instrument, notably through her partnership with fiddler Alasdair Fraser and guest appearances with, among others, Solas and Cape Breton fiddler Natalie MacMaster.

• Vishten is the LeBlanc sisters, Emmanuelle (whistles, octave mandolin, bodhran, keyboards, jaw harp, percussive dance, vocals) and Pastelle (accordion, piano, percussive dance, vocals) from Prince Edward Island, and Pascal Miousse (fiddle, mandolin, guitar, vocals) of Magdalen Island. Their music, which encompasses traditional Acadian-French songs and instrumentals as well as their own compositions, is steeped in the culture and history of the Canadian Maritimes.

• A featured singer in the show this year, Eilís Kennedy, from Dingle, Co. Kerry, won Female Vocal Album of the Year honors from LiveIreland.com for her 2005 CD “Time to Sail.” Kennedy was part of the 2014 “Christmas Celtic Sojourn” as half of the duo Lumiere, with vocalist Pauline Scanlon.

• A former student of venerable Irish step dancer Danny Golden, Cara Butler has toured regularly with The Chieftains and was featured in the 1999 stage production “Dancing on Dangerous Ground.” She and Nathan Pilatzke have drawn accolades through their involvement in The StepCrew, a high-energy show that spotlights Irish and Ottawa Valley step dance and tap.

• The Harney Academy of Irish Dance from Walpole, founded in 1990 by two-time world champion step dancer Liam Harney, has been a fixture of “Christmas Celtic Sojourn” for years. The school’s students and alumni – including Melissa McCarthy, who won the World Irish Dancing Championship age 15-16 category in 2012 – regularly take part in regional, national and international competitions.

For information about “A Christmas Celtic Sojourn,” see wgbh.org/celtic.