get into full swing, a single buzzword crops up again and again: legacy.
It is a thread that runs from the headline show, Jackie Kay's The Maw Broon Monologues, all the way through this year's programme and back to the very roots of the festival.
"It is about the legacy of the movement and what Glasgay! is about," says the event's producer, Steven Thomson.
"Glasgay! came about as a result of artists thinking, 'there's a lot to say about the experience of being gay, lesbian, transsexual or transgender and we shouldn't be prevented from telling our stories'.
"Now 20, years later we've got an Equality Act, a Civil Partnership Act and hopefully quite soon an Equal Marriage Act.
"Things have moved on a lot. I think the biggest change has been in social attitudes.
"The 20th anniversary is a way of looking back on where we started and what Glasgay! particularly has done differently from other festivals."
In Jackie's updated version of The Maw Broon Monologues, Maw Broon, played by Terry Neason, and her alter ego, played by Suzanne Bonnar, are having a mid-life crisis.
To find happiness, they see a therapist and appear on a reality television show. It all sits against a contemporary political backdrop: in this new Coalition era, with the battle for Scottish independence going on, it's a world Maw Broon would have plenty to say about.
"Maw Broon needs to take on Cameroon and Osbroon and she definitely has a view," laughs Steven.
"The great thing Jackie created in this version of The Maw Broon Monologues is the notion of Maw Broon having a doppelganger who is black, who is really Jackie's inner self, questioning all of the traditional aspects of life of the archetypal Maw Broon."
Which brings us back to the subject of legacy again, of the movement and what Glasgay!, a festival that brings 25,000 visitors to Glasgow, is about.
"Jackie is a great example of that, a young woman of Nigerian parents who was adopted by Scottish socialists, brought up in Dundee, and obviously had all sorts of mixed notions about her identity, but writes about Scottishness and diversity and ethnicity in a very funny and accessible way," explains Steven.
Having joining Glasgay! in 2004, this is Steven's 10th festival, and he wants to give more of a Scottish feel and outlook.
That's why he and his fellow organisers decided to ask Scottish writer Stef Smith to look back on those 20 years
Playwright Smith tackles the notion of pseudo gay cures in 'Cured', a special commission for the festival.
The play follows two characters, a fortysomething woman, who is having a mid-life crisis and questioning what her homosexual life actually is, and her lover. Inspired by real accounts of so-called conversion therapy, it is a cleverly written and very funny piece.
Doing work no-one else is doing has become a vital part of the ethos of Glasgay! In another special commission, Donna Rutherford and Martin O'Connor focus on family ties in Wilful Forgetting, which examines the mother and son relationship through family photographs.
On a lighter note, there's a unique film and concert experience with the Royal Scottish National Orchestra playing at a screening of The Wizard of Oz.
And appearing for the first time in Glasgow is cabaret star Tina C, a 'female' US country singer created by Christopher Green, who takes a satirical look at American politics.
Glasgay! patron Craig Hill brings his Tartan About! show to the festival, while stand-ups Vikki Stone and Roisin Conaty also make appearances.
A programme at Glasgow Film Theatre explores the legacy theme, with highlights including I Am Divine, a documentary about John Waters's muse, and Lust in the Dust, a comedy western starring Divine as a dance-hall girl lost in the desert.
"There's something for everyone," says Steven.
"I think Glasgay! in its 20th anniversary is all about a confident programme of artists, some of whom are at the peak of their careers, while others are just starting out.
"They can all confidently say, we're proud of who we are."
l Glasgay! runs at various city venues from October 9 to November 9. Visit www.glasgay.com for details.