Lisa didn't get much sleep last night. It was too cold, though snuggled up beside her boyfriend, lying on a hot-air vent outside a supermarket near Dublin's St Stephen's Green, the 12-year-old managed some respite from early winter.

Her boyfriend is 16-year-old Rory, from Bawnogue in Clondalkin, Co Dublin. Like Lisa, like an estimated 900 other teenagers, his home is Dublin city's streets.

"We sleep in shelters, in laneways or whenever we can on the heater outside the supermarkets," the pretty, slightly chubby, girl nods, sitting on the steps of the Kildare Street Club in St Stephen's Green. "You don't even get to sleep because people do wake you while you're asleep. And the Garda move you on about seven o'clock."

It's coming up to 10 p.m. Redheaded Rory sits on the step below her, hugging into her knees, his chin resting on her lap as she tells how she came to be homeless.

"I'm from Tallaght and I left because I was getting into trouble all the time in school and all. My ma just told me that I'd want to stop or she'd put me in a home. I got suspended from school and the school was taking me back. But I was messing again. So, my step-da came in drunk one night and he said, `Look. Listen. You've got to stop this.' We had this big argument and he told me to pack my bags. He didn't mean it but I took it to my head and I just left."

Too unafraid, giggling at the prospect of being "interviewed for the paper", Lisa rushes on to recount a day with Rory.

"We get up in the morning and go down to Focus Point and we can get a shower there, get something to eat. They'll wash your clothes too for 50p."

Rory interjects that they gave him "this brand-new sleeping bag" that day, retrieving the blue bundle he had secured beneath his legs.

"How much you'd make begging all depends," says Lisa. "You might make £10 or, at the weekends, you might make £30 or £40, though that would be the most. And we'd be begging hard for maybe eight or nine hours. Any money we make we put it together and go for something to eat, and go to the showers in the baths on Tara Street for a wash."

Rory, his voice hoarse, tells that he "ended up on the streets" because he couldn't get on with his brother.

"And I couldn't get on with his wife. She was always bossing me. My mam is up and gone and my da died. But I'm on my own now and I'm my own boss."

Between drags on the cigarette he has just been given by a passerby, he says that when he's around friends he is happy.

"But when I'm on my own I get into a daze. I just think . . . And I get depressed, yeah. All the time, all the time. I will get out of this. When I am 18, I'll get me own place, go on the labour, get a medical card."

He is worried about the winter. "Last winter was horrible when it started snowing and raining and all. Freezing. Sure, I've no socks or nothing on my feet." He lifts his jeans up to show his trainer-clad feet and no socks.

The two say they do not drink. Bright-eyed and lucid, they seem credible. Lisa says she has to stay sober to stay safe and she'd prefer to drink lemonade.

"Up here [the Baggot Street area] you do get trouble. Like one night Rory was gone off to Temple Bar and this man came up and he says: `You'll get nothing sitting there. If you go down further to the canal you'll make decent money.' Then he says: `What are you looking for? Services?' And I says: `No, I don't do anything like that.' And he kept standing at the corner of the road looking at me. That was only the other day."

Outside one of Dublin's city-centre DART stations it is rush hour. Robbie sits on the ground, a thin, soiled yellow blanket draped across his crouched knees. A grubby paper cup rests in his hands. He says he is 15. He looks two years younger.

Brushing his hand through his wave of black hair, he gladly takes a cigarette in exchange for a few minutes of tea-time chat.

"It won't take long though, will it? I want to try and get enough together for a bed and breakfast."

When asked how he ended up here he says he couldn't get on with his father.

"He's an alcoholic and we were always fighting and all. Life on the streets is no better than at home, I suppose, but I don't have to put up with the hassle. They [his parents] think I am in and out of hostels. I have loads of friends in town but mostly I'm on my own. Like, I know them all that live in town, but most of them are on heroin. I don't want to get into that.

"You get loads of weirdos, you do. You get queers coming up to you, asking you: `Do you want to make money?' or `Come on home with me', or whatever. You just tell them to f---k off. You get weirdos messing with you. I got my bag robbed when I was asleep here. I just nodded off and a junkie robbed it.

"Do I get scared?" he says, repeating my question. "You get used to it. Depressed? Sometimes. I'm going to get myself sorted. When I see people going out I think, `I'll be like them, sound.' When I first started this I thought I'd do it for a little while and a year later I'm still here. I can't do this for ever. Even if I get a small job to start with. But you have to have an address and you have to look well."

During the day he says he sometimes sits with flower sellers. "They might buy me tea and coffee or sandwiches. And I talk to the security guards. I know some of them, though a lot of them take liberties because you're homeless. They think because they're on the door they can do anything."

While we are talking, two gardai stop to ask Robbie his name. The young woman garda crouches down to ask him what he's up to. He tells her he's trying to get enough money for a bed.

"Righto," she nods before striding back on her way with her colleague.

"The police don't necessarily hassle you," he explains as soon as they have left, "though most of them do. The only thing they tell you to do is `move on' or `don't be begging'. You can be charged for begging now. I did get the price of a cup of tea off one garda."

As he finishes the cigarette, he turns down the offer of another. "Will you get us a cup of tea, though? Four sugars."

Like Robbie, Rory and Lisa wonder about their future. Lisa says she cannot go back to her mother. "My step-father won't take me back. Anything he says goes. I've seen my mother enough times in town and went over to talk to her. And she says: `I'm not taking you back. It's too much pressure and worry that you'll go again.'

"I do get very depressed. You get homesick like, having no ma, no mother's cuddles."

"She does cry all the time," agrees Rory.

Rory will be 17, he says, "in 12 more days", having been told the day's date. "We'll probably go to the pictures," smiles Lisa looking down at Rory. "And go to McDonalds. And we'll have one of those Happy Meals you have when it's your birthday."

The names of the people interviewed for this article have been changed to protect their identities