Kim, the reigning U.S. Girls' Junior champion, has a one-stroke lead over Amanda Blumenherst, Ashley Knoll and Lorraine Ballerano at the 6,341-yard, par-72 Settindown Creek course of Ansley Golf Club.
'My goal was to shoot 68 or 69,' said Kim. 'I played solidly and made just two mistakes.'
On the 13th hole, Kim double-hit a chip and was given a one-stroke penalty for a bogey. Her only other miscue was a bogey on the fifth hole. She made six birdies on putts ranging from three to 25 feet.
Sophia Sheridan, Annie Thurman-Young, Angela Park, Jennie Lee and Amy Schmucker are two strokes behind Kim at two-under 70.
Jane Park, the defending champion, is one-under-par 71. Park made five birdies against four bogeys Monday. Park is tied with five others.
'I feel a little rusty because I haven't been playing tournament golf,' said Park. 'I think the first two days are about getting to know the course, getting into rhythm for match play.'
Morgan Pressel, the 2005 U.S. Women's Open co-runner up, is even-par 72 along with 12 other golfers.
After Tuesday's second round of stroke play, the field of 156 will be cut to the low 64 scorers, who will advance to match play. The 36-hole final will be played on Sunday.