Chancellor Gordon Brown leads the line-up of politicians, writers and celebrities for the Hay Festival.
The line-up includes former and possibly future prime ministers
Mr Brown, favourite to succeed Tony Blair as prime minister, is confirmed for the literary event's 20th year.
He will discuss his heroes, while former prime minister Sir John Major will talk about his love of cricket.
The line-up includes novelists Doris Lessing and Thomas Keneally, cricketer Imran Khan and comedy veterans Ronnie Corbett and Leslie Phillips.
The festival in the border town of Hay-on-Wye, famed for its 39 bookshops, has grown steadily in size and stature since its launch in 1988.
Then it was an invitation to "a few like-minded friends" to gather in the Welsh countryside for a weekend of literary relaxation.
The town's literature festival is held every June
Now moved to a huge tented field just outside Hay, last year's festival attracted around 130,000 people from the UK and overseas to 392 events.
The full line-up, confirmed by organisers, includes a range of musical events and a film festival which will run alongside the literary event.
As well as Mr Brown's talk, Sir John Major will discuss the early years of his sporting passion, cricket.
Meanwhile, current Conservative leader David Cameron will discuss the environment and shadow foreign secretary William Hague slavery.
It's a 'hello' from Leslie Phillips - and goodnight from him
Nobel Prize winners Wangari Maathai, Wole Soyinka and Derek Walcott are included in this year's programme alongside writers like Kiran Desai, Martin Amis, and Edna O'Brien.
From the world of film and TV, comedy actors Leslie Phillips and Ronnie Corbett and Peter Falk - of Colombo fame - are visiting Hay.
Other famous faces include singer Billy Bragg, and comedians Marcus Brigstocke and Keith Allen who will also be making appearances.
Among the musical highlights will be a return for Sir Bob Geldof, a long-time Hay supporter, Soul II Soul, Senegalese singer Baaba Maal, and the festival will be rounded off by a performance by Wales' own operatic supremo Bryn Terfel, who performed at the first Hay Festival two decades ago.
Ex US president Bill Clinton famously called it "the Woodstock of the mind" when he addressed a packed Hay tent it in 2001.
Last year his former vice-president Al Gore following in his footsteps brought his film An Inconvenient Truth about climate change to the festival stage.
The Welsh festival, which runs from 24 May until 3 June, now has satellite events in Segovia in Spain and Cartagena in Colombia.