`What is theatre?" Two weeks to go before the Fringe Festival lifts off, and Ali Curran is folded into an armchair, sipping wine and asking searching, abstract questions. Clearly, everything is under control, and if it isn't, she's not going to talk about it. Nor is she going to boast about how stressed she is. She has a gift for ignoring the inessential.

Whether it's at the hub of the Edinburgh Fringe - taking soundings among the throng at the Assembly Rooms, or talent-spotting at the Irish Student Drama Festival, the 29-year-old, Belfast-born director of the Fringe cuts straight to the heart of things, passionately focussed on her quest for innovative stage work. To her, this is the essence of the Fringe. As the festival goes into its sixth year - her fourth as director - Curran believes that it is coming of age. "It's a young, mobile event, which is coming together well, building on the learning experiences of the past few years. I'm pleased with the balance of Irish and international work this year, and delighted that we've got established Irish companies like Coisceim in the programme. Our credibility and profile are growing all the time. It's becoming apparent that the Fringe is supporting the mainstream of tomorrow. The next artistic director of the Abbey will be someone who began on the Fringe." Coisceim, Upstate, Daghda, Meridian, Calypso, Pan Pan, Corn Exchange, Island, Team, Bickerstaffe - the roll call of Irish companies in this year's programme includes the creators of some of the most interesting work around, many of whom first came to prominence on the Fringe. Some of these companies did knock on the door of the main Festival first, "not realising", Curran says, "that the Dublin Theatre Festival has altered its programming since the Fringe came into existence."

The emphasis on the Fringe in recent years has been on physical theatre and on performance, while other aspects such as writing and direction have received less attention and have, in many cases, been very weak. Curran stresses that "there's more strong Irish writing this year. Individuals have learned from the experiences of previous years, and recognise that the strength of Irish theatre lies in telling stories, with say one other element used well, for example, design. Meanwhile the international companies can give us their expertise with visual and physical styles - rather than someone's half-baked version of them.

"Finding new writing is crucial. We've got to get in touch with it, perhaps by establishing an award like Corcadorca have recently done. We need to get back to our theatrical roots."

Dance and comedy have been important strands of the Fringe Festival for some time now. Last year Curran introduced a mini-programme of film, but realised that she was competing with the dedicated film festivals for new Irish work, which is primarily what she wanted to include. The experiment gave rise, this year, to a visual art strand, in public spaces around the city centre, which will showcase film and video-based art. "This seems a logical progression. I'm interested in the merging of parameters, in the overlap between different artforms."

So, could the festival become a multiart festival, or will theatre always remain at its core? She says it will, but adds: "That does raise the question of whether theatre in the literal sense still exists. As influences and disciplines merge, the form of theatre changes. All sorts of possibilities are opening up, and judging by the response to the festival over the past few years, audiences want to see innovation. Audiences in Dublin are much more sophisticated than we realise."

Curran's ambitions for the Fringe extend far beyond the annual three-week event. At present, with a budget of £220,000, 23 per cent of which comes from the Arts Council, the rest from partnerships and corporate sponsorship, the festival is not in a position to commission and produce work. It simply receives shows, on a selective basis, and provides a platform for them. "I want to originate and facilitate new work, to invest in the process of creating work all year round, and to respond to the younger companies' needs," Curran says. "So many of them have such exciting ideas, but they can't attract the calibre of performers, directors and designers they need. I want us to invest in the vision of the artist, to facilitate ideas that might take two or three years to come to fruition."

Curran is confident that the festival could become the most significant English-language platform for new work in Europe. "I'm being approached by really interesting international companies who are bypassing Edinburgh. It's a good time to be able to capitalise on the general interest in Dublin from the international sector."

These plans keep Curran excited and motivated. She likes to be in at the beginning of projects, and needs always to be pushing ahead, resisting complacency. While she's wary of the festival becoming associated with one person, in her case it's inevitable that it will. Her drive and commitment have pushed the Fringe Festival into the spotlight, and she has the confidence and personal style to hold her position there. What else would you expect from a statuesque former actor, with a trained voice - "I used to sing with a couple of bands"- who talked her way into becoming the manager and buyer for a chic Belfast clothes shop during her marketing degree and found herself, aged 21, waving cheque books about at London Fashion Week? (That's where she got those dresses . . . )

Recalling a music-in-education project she worked for in her pre-Fringe days, which introduced musical technique to inner-city Dublin children, Curran says, approvingly: "it had a great spirit, a good heart and a conscience". It could be a description of herself.