'At the start my success as a comedian was based on being an American who could do a Cork accent," says Des Bishop. He laughs. "That's not really that impressive considering I'd lived here for years. And sometimes people would respond to my sets with digs about America. They kind of missed the point. I had the same criticisms of America. I didn't care about America. I lived here."

He still does. And over the past decade the Irish-American comedian has found a niche in Irish life as a cutting-edge comedian cum social worker. In The Des Bishop Work Experience he explored what it was like to live on a minimum wage in Celtic Tiger Ireland. He brought comedy workshops to relatively impoverished suburbs of our cities, like Ballymun, Knocknaheneey and Southill in Joy in the Hood, and most recently he went to live in the Gaeltacht to learn the Irish language in In the Name of the Fada, a step that even the most committed home-grown patriot would struggle with. Meanwhile in his shows he turned personal issues like his own testicular cancer and emotional repression into fodder for cathartic public discussion. Bishop seems to be using his comedy for something.

"I suppose in comedy on one end there's Lenny Bruce, where the comedy is all about something else, and on the other end there's," he pauses to think, "Lee Evans, who's purely about entertainment. And that's not a criticism. I don't know where I sit in that Bruce to Evans spectrum, but I do find it easier to be funny when I'm talking about things that concern me, and I happen to be very interested in community. I have to challenge myself to be funny just for the sake of it."

A recovering alcoholic, Bishop credits AA with fostering this social consciousness. "Part of it comes from my mother who was a Democrat and ran a homeless shelter for years," he says. "But if you know anything about the 12 steps you'll know that a key premise is that to keep things you have to give them away. And a lot of it comes from that. When you reach the rock bottom with booze the only thing that's going to help you get through is to actually help other people and share with others who've had that experience. It's a healing energy and it can drive things."

Bishop's drink problem was pretty extreme. He started drinking at the age of 12 and within a couple of years it had already spiralled out of control. "I started doing things you shouldn't be doing at 14," he says, "proper alcoholic things like wetting the bed, fighting, blackouts. By the time I was 17 I realised that nothing good was coming from drinking, but I didn't quit until I was 19. By the time I was in UCC I'd discovered other substances and even my hard-partying friends were distancing themselves from me, and on 16 June 1995 it was game over... Who're you going to hurt at 19? You're going to piss off your parents and your friends, but you're not neglecting your children, you're not robbing banks. But I was getting isolated... and I had to stop."

And that's when community became very important to him. "I was living in Cork and I started being involved with other people who didn't drink or take drugs," he says, "and a lot of those people were from traditionally working-class and even underprivileged neighbourhoods. Then I moved to the Glen and I just started to get really interested in how these areas become completely neglected. I was living in a corporation flat in this forgotten area, but I was inspired by the sense of community in those places. When I moved to Dublin [in 1998] I ended up living in Rialto and got involved in this Rialto area drugs scheme, and the CE schemes were being cut at that time by Mary Harney. I'm fascinated by communities and why they work or don't work. Take the Gaeltacht – they have a social cohesion that you just don't see in other parts of Ireland because they're bound by the language. Somehow their geographic and cultural marginalisation leads to one of the best community atmospheres I've ever experienced."

Belonging seems important to Bishop. Maybe this is because he didn't fit into the Irish-American/Italian-American suburb he grew up in in New York. "My neighbourhood was middle-class by American standards, but Americans think everyone's middle class. By Irish standards it was working class. There was a lot of violence. Peter Gotti, the nephew of John Gotti, was bullying me... well, a group of people connected to him were. They were threatening me on a regular basis based on one of their goombah group having a big problem with me. On top of that I was drinking all the time and then I got kicked out of school. My parents thought I was massively troubled. My cousin, for whatever reason, suggested that I go to boarding school in Ireland and in the desperation of the time we all jumped at it. Nobody got it into their heads, I guess, that Des was leaving home but it happened."

And despite the turmoil and his nascent drink problem he felt oddly at home here. "I was desperate to fit in and to belong and when I came to Ireland I just more naturally had a place. Even though St Peters was a hard enough school... It was in the diocese of Ferns at the end of an era in Irish education; my principal Donal Collins actually went to prison a couple of years later. But I was allowed to be myself there, and I really got into learning. I thought Irish history was fascinating. My whole life I thought that I was Irish, and when I came to Ireland I was desperate to learn everything I could so I could stick it to these guys who were telling me I wasn't. Plus Irish Americans are obsessed with the North. So I just got into learning and that focused me."

He now thinks having been in Wexford at the end of the '80s was critical to his success. "I think having experienced three years at a rural boarding school at the end of the bad times in Ireland is integral to how I see the world and my understanding of Irish society. When I'd go back to New York in the summers it was clear that the standard of living there was so much higher than in Ireland. Our house in New York was warmer and everything was cheaper; all the mod cons were there and my mother's car was nicer than everyone's car in Ireland. I had a unique perspective. Not many people came to Ireland from another culture, saw the end of the bad times, got to watch the country grow, and then come full circle." He corrects himself: "Actually I don't believe that. You just look at Stephen Gately's funeral – a priest in Sherriff Street referring to Stephen's partner... recognising that he was his husband? Ireland's developed in really positive ways that aren't going to change back."

And Bishop himself has contributed to that opening up of Irish society, particularly with his material about his own testicular cancer. "When you discover a funny way of talking about something, usually it just means you've found an interesting way of looking at it. That's what being funny is. Often a comedian's joke goes 'Nama is like... this.' And that comparison helps you to understand. So on that level, whether it's personal or political there's something cathartic and liberating there."

Was cancer a difficult thing to talk about? "I had two very different experiences with the testicular-cancer material. Firstly I tried to do it too soon. So it was too raw. People picked up on that and it didn't work. I used to get resentful at audiences. I'd come off stage thinking: 'Hey having cancer is bad enough and now I'm dying on stage talking about it, you motherf***ers!' Then I realised that I was too connected to it emotionally and they were feeling that emotion. I wasn't dying on stage; they were just feeling bad for me. So I stopped doing it basically. Then in 2003 or 2004 I was stuck for material and thought, 'I'll try some of the cancer stuff again...' And that time it just worked because it no longer affected me emotionally. When I was joking about having one testicle in the early days I really didn't feel comfortable with it, but when I did it a few years later I was so comfortable I didn't give a f*** and that took the emotion out of it and it let people enjoy it. So people who'd had testicular cancer could say 'f***, it's great to laugh at this'. People who knew somebody that had it could say, 'ah this is great because I found that stuff so heavy'. People with lumps went and got them checked; and people who lost loved ones to cancer got a bit of relief because cancer is an overrated word. It became a kind of celebration, but that took time."

Unsurprisingly given his self-awareness and his socially-conscious tendencies, his new DVD Desfunctional deals with both his own emotional maturity and the emotional maturity of the Irish in general. And he's full of ideas for the future. He's keen to make a comedy programme about Irish history and he also wants to do what he did with In the Name of the Fada but with the Chinese language. Which, in a way, would mark the point when an American focusing on Ireland became an Irishman focusing on China.

"I didn't realise how much I felt like an outsider here until I did In the Name of the Fada," he says. "But whatever I felt was definitely healed or alleviated by learning the Irish language and spending time in the Gaeltacht. I felt much more a part of Irish society after that experience.

"Up till then there was this niggling part of me that didn't feel accepted. But now that's gone."

Des Bishop's new DVD 'Desfunctional – Live at the Róisín Dubh' is out now