Kim, the youngest player to reach the final match, defeated 15-year-old Lindy Duncan of Plantation, Fla., 1-up in Saturday's semifinals at Pumpkin Ridge Golf Club.
Schallenberg faced 21-year old Texan Stacy Lewis and won with a 4-foot putt for par on the 19th hole on the 6,380-yard, par-71 Witch Hollow Course.
'I was nervous but I was trying not to show it,' Schallenberg said.
The final 36 holes on Sunday will feature two very different players: Kim is a carefree teenager who didn't know going in that the Amateur was a 'big' tournament, while Schallenberg is consistent and steady.
'I have to stick to my routine and my strategy,' Schallenberg said. 'But I'm curious to see how she handles everything because I didn't play big tournaments at that age.'
Lewis, who has a metal rod in her back after surgery in 2003 to treat scoliosis, ran into trouble on the par-4 No. 8 hole after her second shot went beyond the green and landed in the rough. She wound up losing the hole, and Schallenberg increased her lead to 2-up.
But Lewis rebounded on the back nine and tied the match after 18 holes.
Schallenberg briefly played at the University of Oregon in 2000 but quit because she had a fear of flying. She returned to Germany, where she apprenticed to be a bank clerk but found it 'too boring,' and is now studying international business.
She won the 2005 and 2006 International German Amateur Championships, but has played infrequently in the United States.
After her winning putt under cloudless skies on the par-4 No. 13 hole, Schallenberg embraced her coach.
Lewis, who will be a junior this fall at Arkansas, didn't watch her opponent's final shot, crouching with her head down. Her caddie -- also her dad -- put his arm around her as she slowly walked away.
'I learned I'm a lot better match player than I thought. I struggled with it in the past,' she said, 'but it's pretty fun.'
Afterward, Schallenberg called her parents in Germany, where they were watching via the Internet.
'It was a tough match,' Schallenberg said. 'We both had holes where we struggled. My irons weren't as good as they were (Friday). My putting was OK. I guess I shouldn't complain.'
Duncan, who takes high school classes online so she can devote more time to practice, holed in from the bunker on the par-3 No. 15.
But Kim, who has been living in Arizona and says her hobby is sleeping, birdied the par-4 No. 16 to go 1-up. Then she held on for the victory.
'I didn't know it was that big of a tournament until last night, when there was a commercial on the Golf Channel, and I thought, `Wow, this is a big deal,'' she said. 'I don't even watch golf, I was just looking for myself.'
Duncan was gracious in the loss.
'On two holes, I just kind of gave it to her, and you just can't do that against a player like her,' she said. 'She deserved to win. I hope she goes all the way.'
Last year's Amateur was won by 17-year-old Morgan Pressel at the Ansley Golf Club's Settindown Creek course in Roswell, Ga.
Pumpkin Ridge Golf Club was the site of the U.S. Women's Open in 1997 and 2003. Tiger Woods won the 1996 U.S. Amateur at the club.