Mark Molden, 24, from Bargoed in south Wales, denies nine further charges of indecent assaults on four girls who attended a Salvation Army outdoor pursuits camp between 1997 and 2001.
He told the court he had followed the 15-year-old's directions when he was giving her a lift and she took him to a lane where the assault took place.
The youth leader, who is married, said: "We had a chat by there. She said that she had liked me and we got out of the car and had a cuddle.
"One thing led to another and we had a kiss."
He admitted touching the teenager intimately but said: "It went a bit further - it should not have happened. I realise that.
"I drove her home and met her father, shook his hand. I spoke to her father for a minute or so. He thanked me for bringing her home."
Girls "fancied" leader - claim
Molden denied assaulting a 17-year-old girl who had previously told the court he had put his hands on her breasts as she emerged from a cave and made her perform oral sex on him during an evening "worship walk".
"I've never gone out to grab a handful", he said.
The court also heard nothing improper had happened during the worship walk.
"People at these camps get very emotional. They have a lot of stresses on their shoulders and they find it is a way of relieving stress," he said.
He also claimed the girl and others at the camp had "fancied" him.
He said handprint marks on other girls' T-shirts which the 17-year-old said she saw as they emerged from the cave could have been made by themselves wiping muddy hands on their clothing.
Anonymous e-mail
He said girls had made up accusations against him to back up the 15-year-old girl's story.
Molden had told police during an interview: "People have been intimidating each other to say stuff," the court heard.
The prosecution had previously said Molden had bought the 15-year-old girl credit for her mobile phone so he could send her text messages.
The teenager sent an anonymous e-mail to another Salvation Army leader to say Molden should be taken off the staff.
The jury was also told he was overheard telephoning his wife from a police station after being arrested to say he had not had sexual intercourse with the girl, just "petting".
The trial continues.